case study related to water pollution

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October 21, 2021

The Clean Water Case of the Century

The nation's highest court sided with clean water advocates in a decades-long legal dispute involving a wastewater treatment plant, its pollution discharges, and a partially dead coral reef in Hawaiʻi.

“This decision is a huge victory for clean water,” said David Henkin , the Earthjustice attorney who argued the case before the U.S. Supreme Court.

Our Clients Hawaiʻi Wildlife Fund, Sierra Club-Maui Group, Surfrider Foundation, West Maui Preservation Association Read the Supreme Court Decision

In 2020, the U.S. Supreme Court issued its decision solidifying the Clean Water Act’s place as one of the nation’s most effective environmental laws.

The following year, in the first application of the Supreme Court's test, the Hawai‘i district court reaffirmed protections for the nation's waters.

What started as a local water pollution case could have had disastrous repercussions for clean water across the United States.

What did the U.S. Supreme Court decide?

The U.S. Supreme Court's decision leaves in place vital protections for the nation’s oceans, rivers, and lakes.

The court found that point source discharges to navigable waters through groundwater are regulated under the Clean Water Act. In its decision on County of Maui v. Hawai ʻ i Wildlife Fund , the court held that the Clean Water Act “require[s] a permit if the addition of the pollutants through groundwater is the functional equivalent of a direct discharge from the point source into navigable waters.”

In other words, the Clean Water Act prohibits unpermitted discharge of pollution “into navigable waters, or when the discharge reaches the same result through roughly similar means.”

In doing so, the Court rejected the Trump administration’s polluter-friendly position in the clearest of terms: “We do not see how Congress could have intended to create such a large and obvious loophole in one of the key regulatory innovations of the Clean Water Act.”

The opinion was written by Justice Breyer with a vote of 6-3; with Chief Justice Roberts joining the opinion, along with Ginsburg, Sotomayor, Kagan, and Kavanaugh. (Learn about what happens next with this case, following the Supreme Court's decision.)

Abigail Dillen, President of Earthjustice, explains what happened and what the ruling means:

It’s stunning to think how close we came to a world where industries could just point their pipes straight down into groundwater to dispense of their pollution indirectly into clean water without repercussion. — Abbie Dillen (@AbbieDillen) April 23, 2020

What happened during oral arguments at the U.S. Supreme Court?

Earthjustice attorney David Henkin presented oral arguments in November, before the nine Justices of the U.S. Supreme Court in County of Maui v. Hawaiʻi Wildlife Fund

The Justices posed tough questions to both sides. (Read the transcript.) A summary of the hearing:

• The County’s interpretation of the Clean Water Act is that a “point source” (such as a pipe) must be the thing that delivers pollution for it to be regulated. That, once in groundwater or not straight from the “point source,” the Clean Water Act does not regulate that discharge.
• A few Justices feared the County’s position would create a roadmap for polluters to evade regulation. Justice Breyer asked: What if we end the pipe five feet from the ocean?
• Justice Kagan doubled down, saying nobody would get a permit if they could cut the pipe a few feet short.
• But the Justices also asked Earthjustice attorney Henkin: What should be a definition for a limit to what is regulated? Would this interpretation mean homeowners' septic tanks that leach through groundwater to a river need to get permits under the Clean Water Act (or face stiff fines).
• Henkin explained that pollution that is “traceable” and a “proximate cause” would be regulated and that for three decades, U.S. EPA had gone with that interpretation without millions of homeowners on the hook for pollution from their septic tanks. ( More on the back and forth over the Justice’s questions on limits. )
• The County also deflected responsibility back to the states, saying state groundwater permitting, grant programs, etc., are sufficient to regulate that flows from a point source (such as Maui County’s wastewater wells) through groundwater and to a protected body of water.
• Justice Sotomayor interjected that that’s a problem because it presumes the state will regulate that pollution. Justice Kagan also stated that this case isn’t about relying on state backstops.
• The attorney for the U.S. Government made an analogy about spiking a punch with whiskey . Henkin deftly turned it back around.

The attorney for the U.S. Government made an analogy about spiking a punch with whiskey. Henkin deftly turned it back around. @Earthjustice ’s Sam Sankar explains here. pic.twitter.com/XZrQIjAQM3 — Earthjustice (@Earthjustice) November 6, 2019

• Justices generally seemed to reject the County's extreme position that only pollution direct from a point source is regulated, so pollution sprayed through air or that travels over ground would also be free of Clean Water Act regs. But they seemed unsure how far to go.
• At the end, Justice Sotomayor brought it home asking: What current regulations exist that stop the county from polluting the ocean? It’s definitely happening, and Maui County says the Clean Water Act shouldn't stop them — so are they just going to get away with it? What is being done to stop this?

. @Earthjustice attorney David Henkin gives his final thoughts on defending America's clean water in front of the Supreme Court, likely the biggest day of his career. #CleanWaterActIntact pic.twitter.com/b6k9I8nflc — Earthjustice (@Earthjustice) November 6, 2019

What’s County of Maui v. Hawai‘i Wildlife Fund about?

At its most basic level, this case was about whether a wastewater treatment facility in Maui is violating the Clean Water Act by polluting the ocean indirectly through groundwater.

Since the 1980s, Maui’s Lahaina wastewater treatment facility has been discharging millions of gallons daily of treated sewage into groundwater that reaches the waters off Kahekili Beach, a favorite local snorkeling spot. Depending on local geological conditions, groundwater, which is any water that exists beneath the land’s surface , can flow into major waterways like rivers, streams, and, in the Maui case, the ocean.

In 2012, after years of complaints from the community and unsuccessful negotiations with county officials over the destruction the pollution has caused to the reef and marine life, Earthjustice sued Maui County on behalf of four Maui community groups — Hawaiʻi Wildlife Fund , Sierra Club-Maui Group , Surfrider Foundation , and West Maui Preservation Association .

What is the legal history of this case, before it reached the Supreme Court?

Prior to the U.S. Supreme Court's Apr. 23 decision, two courts ruled in favor of Earthjustice and its clients. In 2016, the U.S. Environmental Protection Agency also agreed with the courts that Maui County was acting illegally.

The county doesn’t dispute that its wastewater pollution reaches the ocean.

Instead, it argued that the discharge of pollution from the facility’s wells does not require Clean Water Act permits because the pollutants do not flow directly into the Pacific Ocean, but indirectly through groundwater. Both the district court and the Ninth Circuit appeals court rejected the county’s claims.

“At bottom, this case is about preventing the county from doing indirectly that which it cannot do directly,” the Ninth Circuit ruled in 2018.

The District of Hawaiʻi court added in its 2014 ruling on the same issue that: “[Maui County’s claim] would, of course, make a mockery of [the Clean Water Act’s regulatory scheme] if [the] authority to control pollution was limited to the bed of the navigable stream itself. The tributaries which join to form the river could then be used as open sewers as far as federal regulation was concerned. No less can be said for groundwater flowing directly into the ocean.”

But Maui County wasn’t giving up. In Feb. 2019, it successfully petitioned the United States Supreme Court to hear the case, an act which now endangers clean water protections writ large.

On Sept. 20, 2019, the Maui County Council voted to settle County of Maui v. Hawaiʻi Wildlife Fund , a decision intended to avoid a standoff at the U.S. Supreme Court that could jeopardize clean water across the United States. But the County of Maui had to officially submit the paperwork to settle the case.

Why does this case matter beyond Maui?

If the Supreme Court had sided with Maui County and overturned the Ninth Circuit’s ruling , it would have allowed industry to freely pollute U.S. waters as long as the pollution isn’t directly discharged into a water source.

Over the past four decades, the U.S. EPA and states across the country have used their Clean Water Act authority to prevent a variety of industries — including wastewater treatment facilities, chemical plants, concentrated animal feeding operations, mines, and oil and gas waste-treatment facilities — from contaminating the nation’s waters via groundwater.

Industry groups are closely watching this case, and the list of groups that have filed amicus briefs to the county’s claims is a who’s who of polluters.

A Supreme Court decision reversing the Ninth Circuit’s ruling would have blown a hole in the Clean Water Act. It would have essentially allowed groundwater to “launder” pollution, allowing polluters to evade responsibility even if their waste contaminates clean water. This was the perverse logic underlying Maui County’s claim that it doesn’t need a permit as long as its pollution runs through the groundwater before reaching the ocean.

Earthjustice attorney David Henkin finds this contention “absurd.”

“According to Maui County, a polluter can avoid the law by taking a pipeline that discharges waste directly into the ocean and cutting it ten feet short of the shoreline,” Henkin said.

Instead of discharging waste directly into the ocean, the polluter is discharging waste onto the beach that then makes its way into the ocean.

“At the end of the day, the water is still polluted,” says Henkin. “And, under the county’s twisted logic, the polluter would get off scot-free.”

Who is on the county’s side?

The list of groups that support Maui County’s efforts to gut the Clean Water Act include Kinder Morgan , Energy Transfer Partners (the company behind the Dakota Access Pipeline ), the U.S. Chamber of Commerce, American Fuel & Petrochemical Manufacturers, National Mining Association, and industrial agricultural business organizations.

The U.S. EPA under the Trump administration has also done an about-face to side with these industries. In April, the agency reversed four decades of agency guidance that the Clean Water Act does regulate discharges of pollution that reach our nation’s waters through groundwater.

4,600 miles due east of Maui, gasoline is flowing into Browns Creek, South Carolina, via contaminated soil and groundwater. Kinder Morgan says that isn’t the corporation’s problem. Justice for the community could hinge on the outcome of this Supreme Court case. Read the story of the small town of Belton, Anderson County.

Who is on the side of clean water?

Eleven different groups that include former U.S. EPA administrators and officials from multiple administrations, 13 states, two counties facing similar pollution, a Native American tribe, craft brewers , law professors, aquatic scientists and scientific societies, and clean water advocates filed briefs in support of Earthjustice and its Maui community clients.

“As the amicus briefs vividly illustrate, this case pits those who are committed to the protection of life-giving, clean water against the Trump administration and polluting industries that want free rein to use groundwater as a sewer to dump their waste and toxic discharges into our nation’s lakes, rivers, and oceans,” Earthjustice attorney David Henkin says.

What happened after the Supreme Court decision?

The case went back to the Ninth Circuit, which then sent it back to the district court.

The next step in the case was for the lower court to decide whether Maui’s discharges meet the new test established by the Supreme Court: whether the sewage plant discharges to the groundwater, through which the sewage migrates inevitably and inexorably to the ocean a quarter mile away, are the functional of direct discharges to the ocean.

On Oct. 20, 2021, the Hawai‘i district court did just that — reaffirming protections for the nation's waters in the first application of the Supreme Court's Maui test.

The court denied the County of Maui’s request to reconsider the court’s Jul. 26, 2021, decision that the county must get a Clean Water Act permit for injection wells at the Lahaina Wastewater Reclamation Facility in West Maui.

“As the first court to apply the Supreme Court’s test, the court sent a strong message of hope to communities seeking to protect their oceans, rivers, and lakes from polluters like Maui County that are fouling those life-giving waters by using groundwater as a sewer,” said Earthjustice attorney David Henkin.

Why does this case matter to me?

Maui County’s argument was not only absurd, it was extremely dangerous. If the Supreme Court had ruled in the county’s favor, it would have jeopardized clean water across the country.

If you care about clean water, then you should care about this case.

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Established in 1988, Earthjustice's Mid-Pacific regional office in Honolulu focuses on environmental and community health issues, including ensuring water is a public trust and achieving a cleaner energy future.

Mid-Pacific Office

Established in 1988, Earthjustice's Mid-Pacific Office, located in Honolulu, Hawaiʻi, works on a broad range of environmental and community health issues, including to ensure water is a public trust and to achieve a cleaner energy future.

The legal case: Lahaina Injection Well

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Challenges to Sustainable Safe Drinking Water: A Case Study of Water Quality and Use across Seasons in Rural Communities in Limpopo Province, South Africa

Joshua n. edokpayi.

1 Department of Hydrology and Water Resources, University of Venda, Thohoyandou 0950, South Africa; [email protected]

2 Department of Civil and Environmental Engineering, University of Virginia, Charlottesville, VA 22904, USA; ude.qud@drelhak (D.M.K.); moc.liamg@320hlc (C.L.H.); ude.ainigriv@sm4rfc (C.R.); ude.ainigriv@e9saj (J.A.S.)

Elizabeth T. Rogawski

3 Department of Public Health Sciences, University of Virginia, Charlottesville, VA 22908, USA; ude.ainigriv@m5rte

4 Division of Infectious Diseases & International Health, University of Virginia, Charlottesville, VA 22908, USA; ude.ainigriv.ccm.liamcsh@v8dr

David M. Kahler

5 Center for Environmental Research and Education, Duquesne University, Pittsburgh, PA 15282, USA

Courtney L. Hill

Catherine reynolds.

6 School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA

Emanuel Nyathi

7 Department of Animal Science, University of Venda, Thohoyandou 0950, South Africa; [email protected]

James A. Smith

John o. odiyo, amidou samie.

8 Department of Microbiology, University of Venda, Thohoyandou 0950, South Africa; [email protected] (A.S.); [email protected] (P.B.)

Pascal Bessong

Rebecca dillingham.

Author Contributions: Conceived and designed the experiments: J.N.E., E.T.R., D.M.K., C.L.H. Performed the experiments: J.N.E., E.T.R., D.M.K., C.L.H., C.R., E.N. Contributed reagents/materials/analysis tools: P.B., E.N., A.S., R.D., J.A.S., J.O.O. Analyzed the data: J.N.E., E.T.R., D.M.K., C.L.H. Wrote the paper: J.N.E., E.T.R., D.M.K., C.L.H. Participated in the editing of the manuscript: J.N.E., E.T.R., D.M.K., C.L.H., P.B., A.S., R.D., J.A.S., J.O.O., E.N., C.R.

Associated Data

Table S2: Membrane-filtration results for E. Coli and total coliforms of water sources,

Table S3: Anion concentrations (mg/L) of water sources,

Table S4: Major metal concentrations (mg/L) of water sources,

Table S5: Trace metal concentrations μg/L) of water sources.

Consumption of microbial-contaminated water can result in diarrheal illnesses and enteropathy with the heaviest impact upon children below the age of five. We aimed to provide a comprehensive analysis of water quality in a low-resource setting in Limpopo province, South Africa. Surveys were conducted in 405 households in rural communities of Limpopo province to determine their water-use practices, perceptions of water quality, and household water-treatment methods. Drinking water samples were tested from households for microbiological contamination. Water from potential natural sources were tested for physicochemical and microbiological quality in the dry and wet seasons. Most households had their primary water source piped into their yard or used an intermittent public tap. Approximately one third of caregivers perceived that they could get sick from drinking water. All natural water sources tested positive for fecal contamination at some point during each season. The treated municipal supply never tested positive for fecal contamination; however, the treated system does not reach all residents in the valley; furthermore, frequent shutdowns of the treatment systems and intermittent distribution make the treated water unreliable. The increased water quantity in the wet season correlates with increased treated water from municipal taps and a decrease in the average contaminant levels in household water. This research suggests that wet season increases in water quantity result in more treated water in the region and that is reflected in residents’ water-use practices.

1. Introduction

Clean and safe drinking water is vital for human health and can reduce the burden of common illnesses, such as diarrheal disease, especially in young children. Unfortunately, in 2010, it was estimated that 1.8 billion people globally drank water that was not safe [ 1 ]. This scenario is most common in developing countries, and the problem is exacerbated in rural areas [ 1 ]. Significant amounts of time are spent by adults and school children upon water abstraction from various sources [ 2 , 3 ]. It is estimated that, in developing countries, women (64%) and girls (8%) spend billions of hours a year collecting water [ 1 ]. The erratic supply of safe drinking and domestic water often affects good hygiene practices. In most developing countries of the world, inadequate supplies of drinking water can contribute to the underage death of children in the region [ 4 – 10 ].

Storage of collected water from rivers, springs, community stand-pipes, and boreholes is a common practice in communities that lack potable water supplies piped into their homes. Even when water is piped into the home, it is often not available on a continuous basis, and water storage is still necessary. Water is stored in various containers which include jerry cans, buckets, drums, basins and local pots [ 11 – 13 ]. It has been reported that when collection of water from sources of high quality is possible, contamination during transport, handling and storage and poor hygienic practices often results and can cause poor health outcomes [ 11 , 13 – 15 ].

South Africa is a semi-arid country that has limited water resources, and the provision of adequate water-supply systems remains a great challenge. In some of the major cities, access to clean and safe drinking water is comparable to what is found in other developed cities, but this is not the case in some cities, towns and most villages where there is constant erratic supply of potable water, and in some cases, there is no water supply system [ 16 ]. Although access to clean and safe drinking water is stipulated as a constitutional right for all South Africans in the country’s constitution [ 17 , 18 ], sustainable access to a potable water supply by millions of South Africans is lacking.

Residents of communities with inadequate water supply are left with no alternative other than to find local sources of drinking water for themselves. Rural areas are the most affected, and residents resort to the collection of water from wells, ponds, springs, lakes, rivers and rainwater harvesting to meet their domestic water needs [ 19 – 24 ]. Water from such sources is often consumed without any form of treatment [ 12 , 19 , 21 ]. However, these alternative sources of drinking water are often vulnerable to point and non-point sources of pollution and are contaminated frequently by fecal matter [ 5 , 19 , 25 ]. A report by the South African Council for Scientific and Industrial Research clearly showed that almost 2.11 million people in South Africa lack access to any safe water infrastructure. The consumption of water from such unimproved sources without treatment constitutes a major public health risk [ 26 ].

Consumption of contaminated drinking water is a cause of diarrheal disease, a leading cause of child mortality in developing countries with about 700,000 deaths of children under the age of 5 reported in 2011 [ 10 , 27 ]. In South Africa, diarrhea is one of the leading causes of death among young children, and this problem is worst in children infected with HIV (Human Immunodeficiency Virus).

The health risks associated with the consumption of unsafe drinking water are not only related to infectious diseases but also to other environmental components such as fluoride, arsenic, lead, cadmium, nitrates and mercury. Excessive consumption of these substances from contaminated drinking water can lead to cancer, dental and skeletal fluorosis, acute nausea, memory lapses, renal failure, anemia, stunted growth, fetal abnormalities and skin rashes [ 16 , 28 ]. Groundwater contamination with high arsenic concentrations have been reported in Bangladesh, and high fluoride concentrations have been reported in the drinking water from various provinces in South Africa [ 28 – 34 ].

Temporary seasonal variations have been reported to influence the levels of contaminants in various water sources differently. The key environmental drivers across the wet and dry seasons include: volume of water, flow, frequency of rainfall events, storm run-off, evaporation and point sources of pollution [ 35 , 36 ]. An increase in storm-water run-off within a river catchment may increase the level of contaminants due to land-use activities. Increased water volume could lead to a decrease in the concentration of contaminants due to the dilution effect. A low incidence of rainfall and high evaporation can cause a contaminant to concentrate in water. Very few water-quality parameters such as turbidity are expected to be higher in the wet season. Other parameters can vary depending on the key environmental drivers. There is paucity of data on the effect of change across seasons on water-use practices among household in rural areas of developing countries.

The geographic area for this study is located 35 km north of Thohoyandou, in Limpopo Province, South Africa. The area is primarily agricultural, such that water contamination by nitrates is a potential concern. In addition, mining operations in the area may contaminate water sources with heavy metals.

The significance of this study lies in the broad characterization of water-quality parameters that could affect human health, which is not restricted to microbiological analysis. In a rural community, the primary concern of drinking water is the microbiological quality of the water and chemical constituents are often considered not as problematic. This study was designed to evaluate a broad spectrum of water-quality constituents of natural water sources and household drinking water used by residents of rural communities in Limpopo Province. We also aimed to determine how water sources and collection practices change between dry and wet seasons within a one-year sampling period.

2. Materials and Methods

2.1. study design.

A baseline census of 10 villages in the Thulamela Municipality of Limpopo Province was completed to identify all households in which there was at least one healthy child under 3 years of age in the household, the child’s caregiver was at least 16 years of age, and the household did not have a permanent, engineered water-treatment system. 415 households that met these eligibility criteria were enrolled for the purposes of a water-treatment intervention trial. The baseline assessment of water-quality and use practices is reported here. Caregivers of the child under 3 years of age were given a questionnaire concerning demographics, socioeconomic status, water-use practices, sanitation and hygiene practices, and perceptions of water quality and health. In addition, a sample of drinking water was taken from a random selection of 25% of the total enrolled households in the dry (June–August 2016) and wet seasons (January–February 2017). The participant population was sorted by community, as a surrogate for water supply, and one-third from each community was randomly selected by a random number generated within Microsoft Excel (Seattle, WA, USA), which was sampled. The protocol used was approved by the Research Ethics Committee at the University of Venda (SMNS/15/MBY/27/0502) and the Institutional Review Board for Health Sciences Research at the University of Virginia (IRB-HSR #18662). Written informed consent was obtained from all participants and consent documentation was made available in English and Tshivenda. The majority of the baseline surveys were conducted in the dry season (approximately April to October). Six-months later, follow-on surveys were conducted at the height of the wet season (approximately November to March; however, the height of the season in 2016–17 was January to March).

2.2. Regional Description of the Study Area

The communities are located in a valley in the Vhembe District of Limpopo Province, South Africa ( Figure 1 ). The valley surrounds the Mutale River in the Soutpansberg Mountains and is located around 22°47′34′′ S and 30°27′01′′ E, in a tropical environment that exhibits a unimodal dry/wet seasonality ( Figure 2 ). In recent years, the area has received annual precipitation between 400 mm and 1100 mm; more importantly, the timing of the precipitation is highly variable ( Figure 2 ). Specifically, in 2010, the annual precipitation was about 750 mm; however, the majority of the precipitation came in March while, traditionally, the wet season begins earlier, in September or October. The year 2011 had the highest precipitation in the six-year period and had the majority of the rainfall in November. The years 2012 and 2015 began with a typical precipitation pattern; however, the rainfall did not continue as it did in 2013 and 2014. Annual temperature of the area also varies, with the highest temperature always recorded in the wet season ( Figure 3 ). There has been much variability of temperature in past years; however, this is beyond the scope of this study. The abbreviations used in Figure 1 and other figures, including the supplementary data and the type of the various water sources used in this study, are shown in Table 1 .

Map of the study area. The communities are all located within the Mutale River watershed. The rivers are indicated in blue, villages outlined in purple, environmental samples in blue squares, tributaries in green circles (which have intermittent flow), watershed boundary in orange. This heavily agricultural area has cultivated areas along both sides of thee Mutale River for the vast majority of the region; the area is shown with green outlines. There are two identified brick-processing areas shown in brown rectangles. Unfortunately, some sites are so close that the markers overlap (as with CR and IR). The location of the community supplies (CA, CB, and CC) are not shown to protect the privacy of those villages. See supplemental information for Google Earth files.

Precipitation trends in the study area. ( a ) Annual precipitation by hydrologic year. Data quality are presented on a scale of zero to unity where the quantity shown represents the proportion of missing or unreliable data in a year; ( b ) Cumulative precipitation for the last five complete years; ( c ) Average monthly precipitation calculated for years with greater than 90% reliable data (bottom right). All data are presented by the standard Southern hemisphere hydrologic year from July to June numbered with the ending year. Data are from the Nwanedzi Natural Reserve at the Luphephe Dam (17 km from the study area) and fire available through the Republic of South Africa, Department of Water and Sanitation, Hydrologic Services ( http://www.dwa.gov.za/Hydrology/ ).

The mean monthly temperature in the region recorded at Punda Milia. ( a ) Mean monthly temperature based on the means from 1962–1984; ( b ) Mean monthly temperature record. Data are available from the National Oceanic and Aviation Administration (U.S.), National Climatic Data Center, Climate Data Online service ( https://www.ncdc.noaa.gov/cdo-web/ ).

Abbreviations, water sources and type.

Agriculture occupies tine greatest land cover in the valley. Mogt households are engaged in some level of farming. Crops cultivated include maize and vegetables, and tree fruits include mangos and citrus fruits. Livestock is prevalent in the area with chickens, goats, and cattle. Smaller animals typically remain closer to households and larger animals graze throughout the region without boundaries. There are several brick-making facilities in the valley that include excavation, brick-forming and drying.

2.3. Water Sources

Drinking water in the study communities is available from a number of municipal and natural sources. The primary source of drinking water for seven of the villages is treated, municipal water. Two of the villages have community-level boreholes, storage tanks, and distribution tanks. An additional village has a borehole as well; however, residents report that, since its installation, the system has never supplied water.

The water for the treatment facility is drawn from behind a weir in the Mutale River and pumped to a retention basin. The water then undergoes standard treatment that includes pH adjustment, flocculation, settling, filtration, and chlorine disinfection. Water is then pumped to two elevated tanks that supply several adjacent regions, including the study area. Specifically, Branch 1 supplies Tshandama, Pile, Mutodani, Tshapasha and Tshibvumo; Branch 2 supplies an intermediary tank that in turn serves Matshavhawe, Muledane and Thongwe. Households can pay for a metered yard connection for the water used; these yard connections can be connected to household plumbing at the household’s discretion. The treated municipal water service is intermittent. Service in Tshandama and Pile was observed to be constant during the wet season and for only about two to three days per week during the dry season. Service in the remaining communities is two to four days per week during the wet season and about two days per week during the dry season. Furthermore, for the past two years, major repairs in the dry season caused the treated municipal water to cease completely. Households typically stored water for the periods when the treated municipal water was off; however, when the municipal water was unavailable for longer periods or not on the anticipated schedule, households obtained water from natural sources. The community-level boreholes provided water almost constantly but were subject to failure and delays in repairs.

Aside from the municipal sources, many residents of three villages have access to a community installed and operated distribution system that delivers water from the adjacent ephemeral rivers throughout the community (CA, CB, and CC). These systems are constructed with 50 mm to 70 mm (5 to 7 × 10 −2 m) high-density polyethylene pipes. Even these community-level schemes provide water on a schedule and sometimes require repair. Another common source of water for the community is springs. These shallow groundwater sources are common in the valley; however, there are communities that do not have a nearby spring. Some springs have had a pipe placed at the outlet to keep the spring open and facilitate filling containers. Researchers did not observe any constructions around the springs to properly isolate them from further contamination, and they are, therefore, not improved water sources. Pit latrines are common in every household throughout the region. Source (TS) is located near these communities while other springs (OS, LS) are located in agricultural areas. Boreholes provide deep groundwater supplies but require a pump. Such systems provide water as long as there is power for the pump and the well is deep enough to withstand seasonal variations. The two clinics in the study area surveyed each relied on a borehole for their water supply. Some residents also collected water directly from the river. The Mutale River is a perennial river; however, the ephemeral rivers, the Tshiombedi, Madade, Pfaleni, and Tshala Rivers, do not flow in the dry season all the way to the floor of the valley. The Tshala River has a diversion to a lined irrigation canal that always carries water, but there is very little flow that remains in the natural channel.

2.4. Water Sampling

The team of community health workers (CHW) that had previously conducted the MAL-ED (Malnutrition and Enteric Diseases) study in the same region [ 37 ] were recruited to assist with the data collection for this study; specifically, the regional description and water sources. These CHWs have an intimate knowledge of the communities as they are residents and have conducted health research in the area. The CHWs provided information on the location and condition of the various water sources in the study communities.

Water sources were tested during two intensive study periods: one in the dry season (June–August, 2016) and the other in the wet season (January–February, 2017). Water sources for investigation were selected based on identification from resident community health workers. Single samples were taken from all 28 identified drinking water sources in the 10 villages and three days of repeated samples were taken from six sources, which represented a range of sources (e.g., surface, borehole, shallow ground, pond, and municipal treated) in the dry season. Single samples of 17 of the original sources and three days of repeated samples were taken from five sources in the wet season, six months later. Some sources were not resampled because the routes to the sources were flooded, and these sources were likely infrequently used during the wet season due to blocked pathways. The wet and dry season measurements gave two different scenarios for water-use behaviors and allowed the researchers to measure representative water-quality parameters.

2.5. Measurement of Physicochemical Parameters

Physicochemical parameters of source water samples were measured in the field by a YSI Professional Plus meter (YSI Inc., Yellow Springs, OH, USA) for pH, dissolved oxygen and conductivity. The probes and meter was calibrated according to the manufacturer’s instructions. Turbidity was measured in the field with an Orbeco-Hellige portable turbidimeter (Orbeco Hellige, Sarasota, FL, USA) (U.S. Environmental Protection Agency method 180.1) [ 38 ]. The turbidimeter was calibrated according to the manufacturer’s instructions. Measured levels were compared to the South African water-quality standards in the regulations [ 39 ], pursuant to the Water Services Act of 1997.

2.6. Microbiological Water-Quality Analysis

Escherichia coli ( E. coli ) and total coliform bacteria were measured in both source and household water samples by membrane filtration according to U.S. Environmental Protection Agency method 10,029 [ 40 ]. Sample cups of the manifold were immersed in a hot-water bath at 100 °C for 15 min. Reverse osmosis water was flushed through the apparatus to cool the sample cups. Paper filter disks of 47 mm (4.7 × 10 −2 m) diameter and 0.45 μm (4.5 × 10 −7 m) pore size (EMD Millipore, Billerica, MA, USA) were removed from their sterile, individual packages and transferred to the surface of the manifold with forceps with an aseptic technique. Blank tests were run with reverse osmosis dilution water. Two dilutions were tested: full-strength (100 mL sample) and 10 −2 (1 mL sample with 99 mL of sterile dilution water) were passed through the filters; this provides a range of zero to 30,000 CFU/100 mL (colony forming units) for both E. coli and total coliforms. The filter paper was placed in a sterile petri dish with absorbent pad with 2 mL (2 × 10 −6 m 3 ) of selective growth media solution (m-ColiBlue24, EMD Millipore, Billerica, MA, USA). The samples were incubated at 35 °C (308.15 K) for 23–25 h. Colonies were counted on the full-strength sample. If colonies exceeded 300 (the maximum valid count), the dilution count was used. In all tests, the dilution value was expected to be within 10 −2 of the full-strength value and the sample was discarded otherwise.

The distribution of the household bacteria levels was evaluated by the (chi square) χ 2 goodness-of-fit test for various subsets of the data. Subsets of the data were then compared by an unpaired Student’s t-test for statistical significance; specifically, wet versus dry season levels as well as any other subsets that could demonstrate differences within the data.

2.7. Major Metals Analysis

A Thermo ICap 6200 Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES, Chemetix Pty Ltd., Johannesburg, South Africa) was used to analyze the major metals in the various samples. The National Institute of Standards and Technology traceable standards (NIST, Gaithersburg, MD, USA) purchased from Inorganic Ventures (INORGANIC VENTURES 300 Technology Drive Christiansburg, Christiansburg, VA, USA) were used to calibrate the instrument for the quantification of selected metals. A NIST-traceable quality control standard from De Bruyn Spectroscopic Solutions, Bryanston, South Africa, were analyzed to verify the accuracy of the calibration before sample analysis, as well as throughout the analysis to monitor drift.

2.8. Trace Metals Analysis

Trace elements were analyzed in source water samples using an Agilent 7900 Quadrupole inductively coupled plasma mass spectrometer (ICP-MS) (Chemetix Pty Ltd., Johannesburg, South Africa). Samples were introduced via a 0.4 mL/min (7 × 10 −9 m 3 s −1 ) micro-mist nebulizer into a Peltier-cooled spray chamber at a temperature of 2 °C (275.15 K), with a carrier gas flow of 1.05 L/min (1.75 × 10 −5 m 3 s −1 ). The elements V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se were analyzed under He-collision mode to remove polyatomic interferences. NIST-traceable standards was used to calibrate the instrument. A NIST-traceable quality control standard of a separate supplier to the main calibration standards was analyzed to verify the accuracy of the calibration before sample analysis.

2.9. Anion Analysis

The anions were analyzed in source-water samples as stated in Edokpayi et al. [ 41 ]. Briefly, an Ion Chromatograph (Metrohm, Johannesburg, South Africa) was used to analyze the concentrations of fluoride, bromide, nitrates, chloride and sulfate. Calibration standards in the range of 1–20 mg/L were prepared from 100 mg/L stock solution containing all the test elements. Prior to analysis, the samples were filtered with a 0.45 μm (4.5 × 10 −7 m) syringe filter. Eluent for the sample run was prepared from sodium bicarbonate and sodium carbonate. A 50 mmol/L sulphuric acid with a flow rate of 0.5 mL/min (8 × 10 −9 m 3 s −1 ) was used as suppressant.

3.1. Socio-Demographic Characteristics of Enrolled Households

We included 405 enrolled households who completed the baseline questionnaire. The majority of caregivers were the mothers (n = 342, 84.4%, median age = 27 years) or grandmothers (n = 51, 12.6%, median age = 50 years) of a young child in the household. Almost all the caregivers had completed at least secondary school education (n = 371, 91.6%). Median monthly income for the entire household was USD$106 (interquartile range (IQR): 71–156). Access to improved sanitation was high. 373 (n = 92.1%) households used an improved pit latrine, and only 19 (n = 4.7%) reported open defecation. However, few households (n = 35,8.6%) reported having a designated place to wash hands near their toilet, and only 29% (n = 119) reported always using soap when washing hands.

Most households had their primary water source ( Table 2 ) piped into their or their neighbor’s yard (dry: n = 226, 62.3%; wet: n = 241, 67.5%) or used a public tap (dry: n = 69, 19.0%; wet: n = 74, 20.7%). A minority (dry: n = 40, 11.0%; wet: n = 19, 5.3%) collected their water directly from rivers, lined canals, or springs. Water was collected by adult women in most households, and it was reported to take a median of 10 min (IQR, both seasons: 5–30) to go to their water source, collect water, and come back in one trip. Three quarters (n = 270, 74.4%) reported that their water source was not continually available in the dry season and two-thirds (n = 234, 65.5%) in the wet season. Almost half (48.9%) reported interruptions in availability that lasted at least 7 days in the dry season and 32.8% in the wet season. Households stored water during interruptions and/or collected water from alternative sources (dry: n = 133, 36.6%; wet: n = 115, 32.2%), which were surface water or shallow groundwater sources (e.g., rivers, lined canals, or springs).

Primary drinking-water sources reported among 363 and 357 households in the study area in the dry and wet seasons, respectively.

Household water was most frequently stored in jerry cans or plastic buckets (n = 363, 89.7%), while 25 households stored water in large drums or plastic tanks (6.2%). Most households reported that their drinking water containers were covered (n = 329, 81.2%), but most used a cup with a handle (n = 281, 69.4%) or their hands (n = 93, 23.0%) for water collection ( Table 3 ). Only 13.3% (n = 54) households reported treating their water, mainly by boiling (n = 22), chlorine (n = 15), or letting the water stand and settle (n = 11).

Mode of water collection from storage containers.

Approximately one-third of caregivers (n = 114, 28.2%) perceived that one can get sick from drinking water (n = 114, 28.2%), and cited diarrhea, schistosomiasis, cholera, fever, vomiting, ear infections, malnutrition, rash, flu and malaria as specific illnesses associated with water. Despite these perceptions, the majority were satisfied with their current water source (n = 297, 73.3%). Those who were unsatisfied cited reasons of insufficient quantity (n = 75), shared water supply (n = 65), uncleanliness (n = 73), cloudiness (n = 47), and bad odor or taste (n = 38).

3.2. Physicochemical and Microbiological Characteristics of the Water Sources

pH and conductivity values ranged between 5.5–7.3 and 24–405 μS/cm in the wet season and 5.8–8.7 and 8–402 μS/cm in the dry season ( Table S1 ). Both pH and conductivity levels were within the recommended limits of the World Health Organization (WHO) for drinking water. The microbiological results and turbidity of the sources tested are presented in Figures ​ Figures4 4 and ​ and5, 5 , and Table S2 , respectively. Microbiological data show contamination with E. coli , a fecal coliform that is potentially pathogenic, and other coliform bacteria.

Membrane filtration results for ( a ) E. coli and ( b ) other coliforms. Data are presented for wet and dry seasons. The four ephemeral rivers (*) have no dry season data because they had no flow; all other sources have the results reported, some of which are zero or near-zero. South African National Standard (SANS 241:1-2015) set the limit of 0 CFU/100 mL for E. coli and 10 CFU/100 mL for total coliforms (CFU/10 −4 m 3 ). Ephemeral rivers that do not flow all the way into the valley are indicated (*) in the dry season.

Turbidity of the water sources in the study area. Two to three measurements were taken during an intensive study period from 13 January 2017 to 4 February 2017 in the wet season and three to four measurements from 5 June 2016 to 15 July 2016 in the dry season. The median measurement of the values is reported here. Ephemeral rivers that do not flow all the way into the valley are indicated (*) in the dry season.

Municipal treated water never showed any detectable colony-forming units (CFU) in a 100 mL sample for E. coli , which is within the Soufh African regulation [ 39 ]. In the wet season, other coliform bacteriaweae detected in the treated wtter (a median valueof 10 CFU/100 mL wac recorded).

Household sample of stored water ( Figure 6 ) show that bacterial contamination levels ranged from no detectable colonies lo the maximum detection level of our protocol of 30,000 CFU/100 mL. There is a trend that total colitorm levels ere lower (during the wet season than the dry season. In the wet season, some communities within the sturdy area had access to constant municipal treated water as monitored by researcher verification of public tap-watcr availebJlity. Othet communities had intermittent access to municipal treated water. Of these honseholds, those that had constant access to treated water at or near their household did have less total coliform in their stored water than those with intermittent services ( Figure 7 ). This neglects the communities that are outside of the municipal treated-water servic e area.

Box-and-whisker plot of total coliform measurements of stored, untreated water in study households in the wet (n = 95) and dry (n = 103) seasons. The box-and-whisker plot indicates the mean (diamond), first, second, and third quartiles (box), and minimum and maximum (whiskers).

Box-and-whisker plot of total coliform measurements of stored water in the wet season in study households in communities that had verified continuous access to municipal treated water versus verified intermittent access.

The total coliform from households in communities with verified continuous treated water had a log-normal distribution (verified by 99%, α = 1 significance level, χ 2 goodness-of-fit test) and were statistically significantly lower (α =1 significance level) than those from households in communities with verified intermittent treated water. Unfortunately, due to the low number of samples from intermittent households, a χ 2 goodness-of-fit test was not meaningful.

3.3. Anion Concentrations

Major anions investigated in the various water sources fell within the recommended guideline values from the WHO [ 42 ]. Fluoride concentrations ranged from below the detection limit (bdl) to 0.82 mg/L in the dry season and to 1.48 mg/L ( Table S3 ) in the wet season. Fluoride levels fell below the threshold limit for fluoride in drinking water from the WHO (1.5 mg/L). Nitrates were also observed within the limit of drinking water, between bdl–17.48 mg/L and bdl–9.72 mg/L in the dry and wet seasons, respectively. Chloride, sulfate and phosphate levels were also present in moderate levels in the various water sources; however, a relatively high concentration of chloride of 462.9 mg/L was determined in the Mutale River in the wet season.

3.4. Trace and Major Elements Composition

Major metals in the various water sources in both seasons complied with the recommended limits of SANS and WHO in drinking water [ 39 , 42 ]. Sodium concentrations in the range of 3.14–41.03 mg/L and 3.02–15.34 mg/L were measured in the wet and the dry seasons, respectively ( Table S4 ). Low values of potassium were measured. Calcium levels ranged between 0.66–33.91 mg/L and 0.53–27.39 mg/L, in the wet and dry seasons, respectively. Low levels of magnesium were also found. Most of the water sources can be classified as soft water owing to the low levels of calcium and magnesium. Aluminium (Al) concentration ranged between 39.18–438 μg/L ( Figure 8 ). Two of the water sources which are community-based water supply systems recorded high levels of Al which exceeded the aesthetic permissible levels of drinking water; others fell within this limit. Similarly, the levels of iron (Fe) varied between 37.30–1354 mg/L and 35.21–1262 mg/L in the wet and the dry seasons, respectively ( Figure 9 ). Some of the sources showed high Fe concentration which exceeded the aesthetic permissible limit of WHO in drinking water [ 42 ]. Two community-based water systems had higher levels of Fe in the wet season as well as the major river in the region (Mutale River) for which high Fe levels were observed in both seasons. One of the clinic boreholes also recorded high levels of Fe above the permissible aesthetic value of (300 mg/L) in both seasons. Temporary seasonal variation was significant only in the levels of Fe and Al. In the wet season, their levels were generally higher than in the dry season. Some other trace metals of concern like Pb, Hg, As, Cd, Cr, Ni, Cu, Mn, Sr were all present at low levels that were below their recommended limits in drinking water for both seasons ( Table S5 ).

Aluminum, measured by an inductively coupled plasma mass spectrometer (ICP-MS), concentration for natural sources in the study area in the wet and dry seasons. The SANS 241 standard is shown (an operational standard is intended for treated water). Sources marked with * are intermittent sources and had no dry-season sample. Other sources have measured concentrations; although they may be too low to plot.

Iron, measured by an ICP-MS, concentration for natural sources in the study area in the wet and dry seasons. The SANS 241 standard is shown. Sources marked with * are intermittent sources and had no dry-season sample. Other sources have measured concentrations; although they may be too low to plot.

4. Discussion

This study provides a comprehensive description of water quality and drinking-water use across seasons in a low-resource community in rural South Africa, including a variety of water sources, ranging from the municipal tap to natural sources and a combination of both when the municipal tap was intermittently available.

Water sources in the study area, aside from the municipal tap, were highly contaminated with E. coli in both the wet and dry seasons; that is, E. coli was above the South African standard (acute health) of 0 CFU/100 mL. It is particularly important to note that E. coli was detected in the boreholes used for water at the local clinics, implying inadequate access to potable water for potentially immunocompromised patients. While the municipal treated water met the E. coli detection limit, the municipal tap did not always fall within the standards of turbidity (≤1 NTU operational and ≤5 NTU aesthetic) and total coliform (≤10 CFU/100 mL) [ 39 ]. These are not direct health risks; however, both measurements can be used to judge the efficacy of the treatment process and suggest that treatment may not have removed other pathogens that were not directly tested, such as protozoan parasites.

While the microbiological contamination of the drinking-water sources was not acceptable, the chemical constituents fell within the South African guidelines [ 39 ]. Calcium, sodium, magnesium and potassium were present in low levels and their concentrations complied with regulatory standards of SANS [ 39 ] and WHO [ 42 ]. Some metals (cadmium, mercury, arsenic and lead) known to be carcinogenic, mutagenic and teratogenic, causing various acute and chronic diseases to humans even at trace levels in drinking water, were investigated and found to be present in very low concentrations that could be of no health risk to the consumers of the various water resources in the region. However, some other metals, such as Al and Fe, were higher in some of the water sources; yet these were still well below the health guidelines for the respective constituent (recommended health levels from SANS and WHO are given as Al < 0.9 mg/L, Fe < 2 mg/L). At these levels, they do not present a health risk but could impart color and significant taste to the water thereby affecting its aesthetic value. Water sources from the community water-supply systems and one of the clinic boreholes recorded higher levels of Al and Fe. The other metals evaluated (copper, zinc, nickel, chromium, Se and Mn) were present in low levels that complied with their recommended limits in drinking water [ 39 , 42 ].

Fluoridation of drinking water is a common practice for oral health in many countries [ 43 ]. The required level of fluoride to reduce incidences of dental caries is in the range of 0.6–0.8 mg/L; however, levels above 1.5 mg/L are associated with dental and skeletal fluorosis [ 43 – 45 ]. The likelihood of fluorosis as a result of high concentration of fluoride is low in these communities, but there could be a high incidence of dental caries since fluoride levels below 0.6 mg/L were measured and some of the water sources did not have fluoride concentrations detectable by the instrument. The National Children’s Health Survey conducted in South Africa showed that 60.3% of children in the age group of 6 years have dental caries. Approximately a third (31.3%) of children aged 4–5 years in Limpopo province have reported cases of dental caries [ 44 , 45 ].

Chloride levels in the water sources do not cause any significant risk to the users except imparting taste to the water for some of the sources that recorded chloride levels above 300 mg/L. Although the study area is characterized by farming activities, the nitrate concentrations measured do not present any health risks. Therefore, the occurrence of methemoglobinemia or blue-baby syndrome as a result of high nitrate levels is unlikely. Other anions were present in moderate levels that would also not constitute any health risks. The levels of all the anions determined in the various sources were lower than the recommended guidelines of WHO [ 42 ].

The microbiological analysis of environmental water sources revealed several trends. Without exception in these samples, bacterial levels in the wet season were higher than in the dry season. This may be caused by greater runoff or infiltration, which carries bacteria from contaminated sources to these water bodies. The upward trend in bacteria in the municipal treated water is not explained by an increase in runoff, but may be due to higher turbidity of the intake for the municipal treated water in the wet season. The treatment facility workers reported to the researchers that they were unable to monitor the quality of the treated water due to instrument failure during the wet season surveillance period.

Water stored in the household showed that the mean total coliform in the wet season was lower than that in the dry season. This trend is opposite to what was observed in the source, or environmental samples. This difference may be explained by the greater availability of treated water in the wet season versus the dry season for approximately 40% of the sampled households ( Figure 7 ). In addition, it is possible that families try to save water during the dry season and do not reject residual water, while the rainy season allows easier washing of the container and for it to be filled with fresh water more regularly.

In the wet season, two communities had consistently treated water available from household connections (usually a tap somewhere in a fence-in yard) or public taps. While the municipal treated water was of lower quality in the wet season than the dry season, the quality was significantly better than most environmental sources.

Another potential explanation is that residents stored their water within their households for a shorter time, which is supported by the use data that showed interruptions in supply were more common and for longer duration in the dry season. The quality of the water stored in households with continuous supply versus intermittent supply also suggests that water availability may play a role in household water quality. This is consistent with research that demonstrates that intermittent water supply introduces contamination into the distribution system in comparison with continuous supply [ 46 ]. Intermittent supply of water may also result in greater quantity and duration of storage at household level, which could increase the likelihood of contamination.

While it has been shown that the quality of water used for drinking in these villages does not meet South African standards, this problem is confounded by evidence from surveys indicating that residents believe they have high-quality water and, therefore, do not use any form of treatment. In the rare case that they do, it is by letting the water stand and settle or by boiling. In addition, even if treated water is collected, there is a risk of recontamination during storage and again when using a cup held by a hand to retrieve water from storage devices, which was common in surveyed homes. In addition, there was little to no detectable residual chlorine in the municipal tap water to prevent recontamination. A previous study performed in an adjacent community showed higher household treatment levels; however, this may have been due to intervention studies in that community (the community in question was excluded from this study because of previous interventions) [ 47 ]. The study also concurred that boiling was the most common method employed.

Given that most of the water from the various sources in this community is contaminated and not treated, there is a high risk of enteric disease in the community. Lack of access to adequate water and sanitation cause exposure to pathogens through water, excreta, toxins, and water-collection and storage pathways, resulting in immense health impacts on communities [ 48 ]. A large burden of death and disability due to lack of access to clean water and sanitation is specifically associated with diarrheal diseases, intestinal helminths, schistosomiasis and trachoma [ 49 ]. While it was found in this study that the study area has a high prevalence of improved sanitation, the likelihood of poor water quality due to intermittent supply and lack of treatment poses a risk of the adverse health effects described. In a previous longitudinal cohort study of children in these villages, most children were exclusively breastfed for only a month or less, and 50% of children had at least one enteropathogen detected in a non-diarrheal stool by three months of age [ 50 ]. Furthermore, the burden of diarrhea was 0.66 episodes per child-year in the first 2 years of life, and stunting prevalence (length-for-age z-score less than −2) in the cohort increased from 12.4% at birth to 35.7% at 24 months [ 50 ]. It is likely that contaminated water contributed to the observed pathogen burden and stunting prevalence in these communities. In summary, microbiological contamination of the drinking water is high in the study area, and risk from other chemical constituents is low. Therefore, engineered solutions should focus more on improving the microbiological quality of the drinking water.

The intermittent supply in municipal tap water, inadequate water quality from alternative sources, and the risk of recontamination during storage suggest a need for a low-cost, point-of-use water-treatment solution to be used at the household level in these communities. Access to clean drinking water will contribute to improving the health of young children who are at highest risk of the morbidity and mortality associated with waterborne diseases. Such an intervention may go beyond the prevention of diarrhea by impacting long-term outcomes such as environmental enteropathy, poor growth and cognitive impairment, which have been associated with long-term exposure to enteropathogens [ 51 ]. This is supported by a recent finding that access to improved water and sanitation was associated with improvements on a receptive vocabulary test at 1, 5 and 8 years of age among Peruvian, Ethiopian, Vietnamese and Indian children [ 52 ]. The implementation of point-of-use water treatment devices would ensure that water is safe to drink before consumption in the homes of these villages, improving child health and development.

5. Conclusions

This study was comprehensive in the assessment of all aspects of water quality and corresponding water-use practices in rural areas of Limpopo Province. The results obtained indicate that microbiological water quality is more likely to have adverse effect on the consumers of natural water without adequate treatment, as E. coli was determined in all the natural water sources. Local needs assessments are critical to understanding local variability in water quality and developing appropriate interventions. Interventions to ensure clean and safe drinking water in rural areas of Limpopo province should, first and foremost, consider microbiological contamination as a priority. Risk-assessment studies of the impact of water quality on human health is, therefore, recommended.

Supplementary Material

Tables s1 through s5.

Table S1: Physical characteristics of water sources. Two to three measurements were taken during an intensive study period from 13 January 2017 to 4 February 2017 in the wet season, and three to four measurements from 5 June 2016 to 15 July 2016 in the dry season. The median measurement of the values is reported here. Sites with missing samples, such as ephemeral rivers that do not flow all the way into the valley in the dry season, are indicated (*). Sites with missing data due to instrument failure are indicated (#). Values that were below the detection limit are indicated (bdl). South African regulation (SANS 241:1-2015) and the World Health Organization Recommended Guidelines for Drinking Water Quality (Fourth Edition) are listed; parameters not listed are indicated (nl),

Acknowledgments:

This project was funded by the Fogarty International Center (FIC) of the National Institutes of Health (NIH) (Award Number D43 TW009359), National Science Foundation (NSF) (Award Number CBET-1438619), the Center for Global Health at the University of Virginia (CGH), and the University of Virginia’s Jefferson Public Fellows (JPC) program. The content is solely the responsibility of the authors and does not represent the official views of the funders. The authors also acknowledge the tireless work of the community field workers who undertook interventions and collected all of the survey data. The authors also acknowledge A. Gaylord, N. Khuliso, S. Mammburu, K. McCain and E. Stinger, who performed much of the water-quality analysis and T. Singh, who supported the laboratory analysis for inorganic materials.

Supplementary Materials: The following are available online at www.mdpi.com/s1 ,

Conflicts of Interest: The authors declare no conflict of interest.

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Water Pollution and its Sources, Effects & Management: A Case Study of Delhi

Shahid Ahmed and Saba Ismail (2018) 'Water Pollution and its Sources, Effects & Management: A Case Study of Delhi', International Journal of Current Advanced Research, 07(2), pp. 10436-10442

7 Pages Posted: 31 Mar 2018

Shahid Ahmed

Jamia Millia Islamia - Economics

Saba Ismail

Jamia Millia Islamia

Date Written: 2018

Water pollution is a national and global issue. Humans and all living species in the world are facing worst results of polluted water. The present study investigates the level of awareness about water pollution in Delhi, its causes, its health effects and solutions among the youth in Delhi. The paper has used primary data collected through a schedule from university/college students in Delhi. The study concludes that the majority of educated youth (94%) perceives water pollution as environmental challenge and 52% respondents ranked it (1-3) as most important threat. The study identified dumping of waste as one of the most important causes of water pollution; untreated sewage as the second most important cause of water pollution and industrial discharge as the third most important cause of water pollution. The study identified Typhoid, Diarrhoea, Dengue, Cholera, Jaundice, Malaria, Chikungunya, etc are associated with water pollution on the basis of survey. The study suggests awareness campaign involving citizens and strict enforcement of environmental laws by concerned agencies as the appropriate solution to control environment degradation. It is recommended that there should be proper waste disposal system and waste should be treated before entering in to river and water bodies.

Keywords: Environment Sustainability, Water Pollution, Health Effects

JEL Classification: Q50, Q53, I12

Suggested Citation: Suggested Citation

Shahid Ahmed (Contact Author)

Jamia millia islamia - economics ( email ).

Jamia Nagar New Delhi, 110025 India

HOME PAGE: http://jmi.ac.in/economics/faculty-members/Prof_Shahid_Ahmed-1783

Jamia Millia Islamia ( email )

Jamia Nagar, New Delhi Delhi, 110025 India

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Effects of water pollution on human health and disease heterogeneity: a review.

• 1 Research Center for Economy of Upper Reaches of the Yangtse River/School of Economics, Chongqing Technology and Business University, Chongqing, China
• 2 School of Economics and Management, Huzhou University, Huzhou, China

Background: More than 80% of sewage generated by human activities is discharged into rivers and oceans without any treatment, which results in environmental pollution and more than 50 diseases. 80% of diseases and 50% of child deaths worldwide are related to poor water quality.

Methods: This paper selected 85 relevant papers finally based on the keywords of water pollution, water quality, health, cancer, and so on.

Results: The impact of water pollution on human health is significant, although there may be regional, age, gender, and other differences in degree. The most common disease caused by water pollution is diarrhea, which is mainly transmitted by enteroviruses in the aquatic environment.

Discussion: Governments should strengthen water intervention management and carry out intervention measures to improve water quality and reduce water pollution’s impact on human health.

Introduction

Water is an essential resource for human survival. According to the 2021 World Water Development Report released by UNESCO, the global use of freshwater has increased six-fold in the past 100 years and has been growing by about 1% per year since the 1980s. With the increase of water consumption, water quality is facing severe challenges. Industrialization, agricultural production, and urban life have resulted in the degradation and pollution of the environment, adversely affecting the water bodies (rivers and oceans) necessary for life, ultimately affecting human health and sustainable social development ( Xu et al., 2022a ). Globally, an estimated 80% of industrial and municipal wastewater is discharged into the environment without any prior treatment, with adverse effects on human health and ecosystems. This proportion is higher in the least developed countries, where sanitation and wastewater treatment facilities are severely lacking.

Sources of Water Pollution

Water pollution are mainly concentrated in industrialization, agricultural activities, natural factors, and insufficient water supply and sewage treatment facilities. First, industry is the main cause of water pollution, these industries include distillery industry, tannery industry, pulp and paper industry, textile industry, food industry, iron and steel industry, nuclear industry and so on. Various toxic chemicals, organic and inorganic substances, toxic solvents and volatile organic chemicals may be released in industrial production. If these wastes are released into aquatic ecosystems without adequate treatment, they will cause water pollution ( Chowdhary et al., 2020 ). Arsenic, cadmium, and chromium are vital pollutants discharged in wastewater, and the industrial sector is a significant contributor to harmful pollutants ( Chen et al., 2019 ). With the acceleration of urbanization, wastewater from industrial production has gradually increased. ( Wu et al., 2020 ). In addition, water pollution caused by industrialization is also greatly affected by foreign direct investment. Industrial water pollution in less developed countries is positively correlated with foreign direct investment ( Jorgenson, 2009 ). Second, water pollution is closely related to agriculture. Pesticides, nitrogen fertilizers and organic farm wastes from agriculture are significant causes of water pollution (RCEP, 1979). Agricultural activities will contaminate the water with nitrates, phosphorus, pesticides, soil sediments, salts and pathogens ( Parris, 2011 ). Furthermore, agriculture has severely damaged all freshwater systems in their pristine state ( Moss, 2008 ). Untreated or partially treated wastewater is widely used for irrigation in water-scarce regions of developing countries, including China and India, and the presence of pollutants in sewage poses risks to the environment and health. Taking China as an example, the imbalance in the quantity and quality of surface water resources has led to the long-term use of wastewater irrigation in some areas in developing countries to meet the water demand of agricultural production, resulting in serious agricultural land and food pollution, pesticide residues and heavy metal pollution threatening food safety and Human Health ( Lu et al., 2015 ). Pesticides have an adverse impact on health through drinking water. Comparing pesticide use with health life Expectancy Longitudinal Survey data, it was found that a 10% increase in pesticide use resulted in a 1% increase in the medical disability index over 65 years of age ( Lai, 2017 ). The case of the Musi River in India shows a higher incidence of morbidity in wastewater-irrigated villages than normal-water households. Third, water pollution is related to natural factors. Taking Child Loess Plateau as an example, the concentration of trace elements in water quality is higher than the average world level, and trace elements come from natural weathering and manufacture causes. Poor river water quality is associated with high sodium and salinity hazards ( Xiao et al., 2019 ). The most typical water pollution in the middle part of the loess Plateau is hexavalent chromium pollution, which is caused by the natural environment and human activities. Loess and mudstone are the main sources, and groundwater with high concentrations of hexavalent chromium is also an important factor in surface water pollution (He et al., 2020). Finally, water supply and sewage treatment facilities are also important factors affecting drinking water quality, especially in developing countries. In parallel with China rapid economic growth, industrialization and urbanization, underinvestment in basic water supply and treatment facilities has led to water pollution, increased incidence of infectious and parasitic diseases, and increased exposure to industrial chemicals, heavy metals and algal toxins ( Wu et al., 1999 ). An econometric model predicts the impact of water purification equipment on water quality and therefore human health. When the proportion of household water treated with water purification equipment is reduced from 100% to 90%, the expected health benefits are reduced by up to 96%.. When the risk of pretreatment water quality is high, the decline is even more significant ( Brown and Clasen, 2012 ).

To sum up, water pollution results from both human and natural factors. Various human activities will directly affect water quality, including urbanization, population growth, industrial production, climate change, and other factors ( Halder and Islam, 2015 ) and religious activities ( Dwivedi et al., 2018 ). Improper disposal of solid waste, sand, and gravel is also one reason for decreasing water quality ( Ustaoğlua et al., 2020 ).

Impact of Water Pollution on Human Health

Unsafe water has severe implications for human health. According to UNESCO 2021 World Water Development Report , about 829,000 people die each year from diarrhea caused by unsafe drinking water, sanitation, and hand hygiene, including nearly 300,000 children under the age of five, representing 5.3 percent of all deaths in this age group. Data from Palestine suggest that people who drink municipal water directly are more likely to suffer from diseases such as diarrhea than those who use desalinated and household-filtered drinking water ( Yassin et al., 2006 ). In a comparative study of tap water, purified water, and bottled water, tap water was an essential source of gastrointestinal disease ( Payment et al., 1997 ). Lack of water and sanitation services also increases the incidence of diseases such as cholera, trachoma, schistosomiasis, and helminthiasis. Data from studies in developing countries show a clear relationship between cholera and contaminated water, and household water treatment and storage can reduce cholera ( Gundry et al., 2004 ). In addition to disease, unsafe drinking water, and poor environmental hygiene can lead to gastrointestinal illness, inhibiting nutrient absorption and malnutrition. These effects are especially pronounced for children.

Purpose of This Paper

More than two million people worldwide die each year from diarrhoeal diseases, with poor sanitation and unsafe drinking water being the leading cause of nearly 90% of deaths and affecting children the most (United Nations, 2016). More than 50 kinds of diseases are caused by poor drinking water quality, and 80% of diseases and 50% of child deaths are related to poor drinking water quality in the world. However, water pollution causes diarrhea, skin diseases, malnutrition, and even cancer and other diseases related to water pollution. Therefore, it is necessary to study the impact of water pollution on human health, especially disease heterogeneity, and clarify the importance of clean drinking water, which has important theoretical and practical significance for realizing sustainable development goals. Unfortunately, although many kinds of literature focus on water pollution and a particular disease, there is still a lack of research results that systematically analyze the impact of water pollution on human health and the heterogeneity of diseases. Based on the above background and discussion, this paper focuses on the effect of water pollution on human health and its disease heterogeneity.

Materials and Methods

Search process.

This article uses keywords such as “water,” “water pollution,” “water quality,” “health,” “diarrhea,” “skin disease,” “cancer” and “children” to search Web of Science and Google Scholar include SCI and SSCI indexed papers, research reports, and works from 1990 to 2021.

Inclusion-Exclusion Criteria and Data Extraction Process

The existing literature shows that water pollution and human health are important research topics in health economics, and scholars have conducted in-depth research. As of 30 December 2021, 104 related literatures were searched, including research papers, reviews and conference papers. Then, according to the content relevancy, 19 papers were eliminated, and 85 papers remained. The purpose of this review is to summarize the impact of water pollution on human health and its disease heterogeneity and to explore how to improve human health by improving water pollution control measures.

Information extracted from all included papers included: author, publication date, sample country, study methodology, study purpose, and key findings. All analysis results will be analyzed according to the process in Figure 1 .

FIGURE 1 . Data extraction process (PRISMA).

The relevant information of the paper is exported to the Excel database through Endnote, and the duplicates are deleted. The results were initially extracted by one researcher and then cross-checked by another researcher to ensure that all data had been filtered and reviewed. If two researchers have different opinions, the two researchers will review together until a final agreement is reached.

Quality Assessment of the Literature

The JBI Critical Appraisal Checklist was used to evaluate the quality of each paper. The JBI (Joanna Briggs Institute) key assessment tool was developed by the JBI Scientific Committee after extensive peer review and is designed for system review. All features of the study that meet the following eight criteria are included in the final summary:1) clear purpose; 2) Complete information of sample variables; 3) Data basis; 4) the validity of data sorting; 5) ethical norms; (6); 7) Effective results; 8) Apply appropriate quantitative methods and state the results clearly. Method quality is evaluated by the Yes/No questions listed in the JBI Key Assessment List. Each analysis paper received 6 out of 8.

The quality of drinking water is an essential factor affecting human health. Poor drinking water quality has led to the occurrence of water-borne diseases. According to the World Health Organization (WHO) survey, 80% of the world’s diseases and 50% of the world’s child deaths are related to poor drinking water quality, and there are more than 50 diseases caused by poor drinking water quality. The quality of drinking water in developing countries is worrying. The negative health effects of water pollution remain the leading cause of morbidity and mortality in developing countries. Different from the existing literature review, this paper mainly studies the impact of water pollution on human health according to the heterogeneity of diseases. We focuses on diarrhea, skin diseases, cancer, child health, etc., and sorts out the main effects of water pollution on human health ( Table 1 ).

TABLE 1 . Major studies on the relationship between water pollution and health.

Water Pollution and Diarrhea

Diarrhea is a common symptom of gastrointestinal diseases and the most common disease caused by water pollution. Diarrhea is a leading cause of illness and death in young children in low-income countries. Diarrhoeal diseases account for 21% of annual deaths among children under 5 years of age in developing countries ( Waddington et al., 2009 ). Many infectious agents associated with diarrhea are directly related to contaminated water ( Ahmed and Ismail, 2018 ). Parasitic worms present in non-purifying drinking water when is consumed by human beings causes diseases ( Ansari and Akhmatov., 2020 ) . It was found that treated water from water treatment facilities was associated with a lower risk of diarrhea than untreated water for all ages ( Clasen et al., 2015 ). For example, in the southern region of Brazil, a study found that factors significantly associated with an increased risk of mortality from diarrhoea included lack of plumbed water, lack of flush toilets, poor housing conditions, and overcrowded households. Households without access to piped water had a 4.8 times higher risk of infant death from diarrhea than households with access to piped water ( Victora et al., 1988 )

Enteroviruses exist in the aquatic environment. More than 100 pathogenic viruses are excreted in human and animal excreta and spread in the environment through groundwater, estuarine water, seawater, rivers, sewage treatment plants, insufficiently treated water, drinking water, and private wells ( Fong and Lipp., 2005 ). A study in Pakistan showed that coliform contamination was found in some water sources. Improper disposal of sewage and solid waste, excessive use of pesticides and fertilizers, and deteriorating pipeline networks are the main causes of drinking water pollution. The main source of water-borne diseases such as gastroenteritis, dysentery, diarrhea, and viral hepatitis in this area is the water pollution of coliform bacteria ( Khan et al., 2013 ). Therefore, the most important role of water and sanitation health interventions is to hinder the transmission of diarrheal pathogens from the environment to humans ( Waddington et al., 2009 ).

Meta-analyses are the most commonly used method for water quality and diarrhea studies. It was found that improving water supply and sanitation reduced the overall incidence of diarrhea by 26%. Among Malaysian infants, having clean water and sanitation was associated with an 82% reduction in infant mortality, especially among infants who were not breastfed ( Esrey et al., 1991 ). All water quality and sanitation interventions significantly reduced the risk of diarrhoeal disease, and water quality interventions were found to be more effective than previously thought. Multiple interventions (including water, sanitation, and sanitation measures) were not more effective than single-focus interventions ( Fewtrell and Colford., 2005 ). Water quality interventions reduced the risk of diarrhoea in children and reduced the risk of E. coli contamination of stored water ( Arnold and Colford., 2007 ). Interventions to improve water quality are generally effective in preventing diarrhoea in children of all ages and under 5. However, some trials showed significant heterogeneity, which may be due to the research methods and their conditions ( Clasen et al., 2007 ).

Water Pollution and Skin Diseases

Contrary to common sense that swimming is good for health, studies as early as the 1950s found that the overall disease incidence in the swimming group was significantly higher than that in the non-swimming group. The survey shows that the incidence of the disease in people under the age of 10 is about 100% higher than that of people over 10 years old. Skin diseases account for a certain proportion ( Stevenson, 1953 ). A prospective epidemiological study of beach water pollution was conducted in Hong Kong in the summer of 1986–1987. The study found that swimmers on Hong Kong’s coastal beaches were more likely than non-swimmers to complain of systemic ailments such as skin and eyes. And swimming in more polluted beach waters has a much higher risk of contracting skin diseases and other diseases. Swimming-related disease symptom rates correlated with beach cleanliness ( Cheung et al., 1990 ).

A study of arsenic-affected villages in the southern Sindh province of Pakistan emphasized that skin diseases were caused by excessive water quality. By studying the relationship between excessive arsenic in drinking water caused by water pollution and skin diseases (mainly melanosis and keratosis), it was found that compared with people who consumed urban low-arsenic drinking water, the hair of people who consumed high-arsenic drinking water arsenic concentration increased significantly. The level of arsenic in drinking water directly affects the health of local residents, and skin disease is the most common clinical complication of arsenic poisoning. There is a correlation between arsenic concentrations in biological samples (hair and blood) from patients with skin diseases and intake of arsenic-contaminated drinking water ( Kazi et al., 2009 ). Another Bangladesh study showed that many people suffer from scabies due to river pollution ( Hanif et al., 2020 ). Not only that, but water pollution from industry can also cause skin cancer ( Arif et al., 2020 ).

Studies using meta-analysis have shown that exposure to polluted Marine recreational waters can have adverse consequences, including frequent skin discomfort (such as rash or itching). Skin diseases in swimmers may be caused by a variety of pathogenic microorganisms ( Yau et al., 2009 ). People (swimmers and non-swimmers) exposed to waters above threshold levels of bacteria had a higher relative risk of developing skin disease, and levels of bacteria in seawater were highly correlated with skin symptoms.

Studies have also suggested that swimmers are 3.5 times more likely to report skin diseases than non-swimmers. This difference may be a “risk perception bias” at work on swimmers, who are generally aware that such exposure may lead to health effects and are more likely to detect and report skin disorders. It is also possible that swimmers exaggerated their symptoms, reporting conditions that others would not classify as true skin disorders ( Fleisher and Kay. 2006 ).

Water Pollution and Cancer

According to WHO statistics, the number of cancer patients diagnosed in 2020 reached 19.3 million, while the number of deaths from cancer increased to 10 million. Currently, one-fifth of all global fevers will develop cancer during their lifetime. The types and amounts of carcinogens present in drinking water will vary depending on where they enter: contamination of the water source, water treatment processes, or when the water is delivered to users ( Morris, 1995 ).

From the perspective of water sources, arsenic, nitrate, chromium, etc. are highly associated with cancer. Ingestion of arsenic from drinking water can cause skin cancer and kidney and bladder cancer ( Marmot et al., 2007 ). The risk of cancer in the population from arsenic in the United States water supply may be comparable to the risk from tobacco smoke and radon in the home environment. However, individual susceptibility to the carcinogenic effects of arsenic varies ( Smith et al., 1992 ). A high association of arsenic in drinking water with lung cancer was demonstrated in a northern Chilean controlled study involving patients diagnosed with lung cancer and a frequency-matched hospital between 1994 and 1996. Studies have also shown a synergistic effect of smoking and arsenic intake in drinking water in causing lung cancer ( Ferreccio et al., 2000 ). Exposure to high arsenic levels in drinking water was also associated with the development of liver cancer, but this effect was not significant at exposure levels below 0.64 mg/L ( Lin et al., 2013 ).

Nitrates are a broader contaminant that is more closely associated with human cancers, especially colorectal cancer. A study in East Azerbaijan confirmed a significant association between colorectal cancer and nitrate in men, but not in women (Maleki et al., 2021). The carcinogenic risk of nitrates is concentration-dependent. The risk increases significantly when drinking water levels exceed 3.87 mg/L, well below the current drinking water standard of 50 mg/L. Drinking water with nitrate concentrations lower than current drinking water standards also increases the risk of colorectal cancer ( Schullehner et al., 2018 ).

Drinking water with high chromium content will bring high carcinogenicity caused by hexavalent chromium to residents. Drinking water intake of hexavalent chromium experiments showed that hexavalent chromium has the potential to cause human respiratory cancer. ( Zhitkovich, 2011 ). A case from Changhua County, Taiwan also showed that high levels of chromium pollution were associated with gastric cancer incidence ( Tseng et al., 2018 ).

There is a correlation between trihalomethane (THM) levels in drinking water and cancer mortality. Bladder and brain cancers in both men and women and non-Hodgkin’s lymphoma and kidney cancer in men were positively correlated with THM levels, and bladder cancer mortality had the strongest and most consistent association with THM exposure index ( Cantor et al., 1978 ).

From the perspective of water treatment process, carcinogens may be introduced during chlorine treatment, and drinking water is associated with all cancers, urinary cancers and gastrointestinal cancers ( Page et al., 1976 ). Chlorinated byproducts from the use of chlorine in water treatment are associated with an increased risk of bladder and rectal cancer, with perhaps 5,000 cases of bladder and 8,000 cases of rectal cancer occurring each year in the United States (Morris, 1995).

The impact of drinking water pollutants on cancer is complex. Epidemiological studies have shown that drinking water contaminants, such as chlorinated by-products, nitrates, arsenic, and radionuclides, are associated with cancer in humans ( Cantor, 1997 ). Pb, U, F- and no3- are the main groundwater pollutants and one of the potential causes of cancer ( Kaur et al., 2021 ). In addition, many other water pollutants are also considered carcinogenic, including herbicides and pesticides, and fertilizers that contain and release nitrates ( Marmot et al., 2007 ). A case from Hebei, China showed that the contamination of nitrogen compounds in well water was closely related to the use of nitrogen fertilizers in agriculture, and the levels of three nitrogen compounds in well water were significantly positively correlated with esophageal cancer mortality ( Zhang et al., 2003 ).

In addition, due to the time-lag effect, the impact of watershed water pollution on cancer is spatially heterogeneous. The mortality rate of esophageal cancer caused by water pollution is significantly higher downstream than in other regions due to the impact of historical water pollution ( Xu et al., 2019 ). A study based on changes in water quality in the watershed showed that a grade 6 deterioration in water quality resulted in a 9.3% increase in deaths from digestive cancer. ( Ebenstein, 2012 ).

Water Pollution and Child Health

Diarrhea is a common disease in children. Diarrhoeal diseases (including cholera) kill 1.8 million people each year, 90 per cent of them children under the age of five, mostly in developing countries. 88% of diarrhoeal diseases are caused by inadequate water supply, sanitation and hygiene (Team, 2004). A large proportion of these are caused by exposure to microbially infected water and food, and diarrhea in infants and young children can lead to malnutrition and reduced immune resistance, thereby increasing the likelihood of prolonged and recurrent diarrhea ( Marino, 2007 ). Pollution exposure experienced by children during critical periods of development is associated with height loss in adulthood ( Zaveri et al., 2020 ). Diseases directly related to water and sanitation, combined with malnutrition, also lead to other causes of death, such as measles and pneumonia. Child malnutrition and stunting due to inadequate water and sanitation will continue to affect more than one-third of children in the world ( Bartlett, 2003 ). A study from rural India showed that children living in households with tap water had significantly lower disease prevalence and duration ( Jalan and Ravallion, 2003 ).

In conclusion, water pollution is a significant cause of childhood diseases. Air, water, and soil pollution together killed 940,000 children worldwide in 2016, two-thirds of whom were under the age of 5, and the vast majority occurred in low- and middle-income countries ( Landrigan et al., 2018 ). The intensity of industrial organic water pollution is positively correlated with infant mortality and child mortality in less developed countries, and industrial water pollution is an important cause of infant and child mortality in less developed countries ( Jorgenson, 2009 ). In addition, arsenic in drinking water is a potential carcinogenic risk in children (García-Rico et al., 2018). Nitrate contamination in drinking water may cause goiter in children ( Vladeva et al.., 2000 ).

Discussions

This paper reviews the environmental science, health, and medical literature, with a particular focus on epidemiological studies linking water quality, water pollution, and human disease, as well as studies on water-related disease morbidity and mortality. At the same time, special attention is paid to publications from the United Nations and the World Health Organization on water and sanitation health research. The purpose of this paper is to clarify the relationship between water pollution and human health, including: The relationship between water pollution and diarrhea, the mechanism of action, and the research situation of meta-analysis; The relationship between water pollution and skin diseases, pathogenic factors, and meta-analysis research; The relationship between water pollution and cancer, carcinogenic factors, and types of cancer; The relationship between water pollution and Child health, and the major childhood diseases caused.

A study of more than 100 literatures found that although factors such as country, region, age, and gender may have different influences, in general, water pollution has a huge impact on human health. Water pollution is the cause of many human diseases, mainly diarrhoea, skin diseases, cancer and various childhood diseases. The impact of water pollution on different diseases is mainly reflected in the following aspects. Firstly, diarrhea is the most easily caused disease by water pollution, mainly transmitted by enterovirus existing in the aquatic environment. The transmission environment of enterovirus depends on includes groundwater, river, seawater, sewage, drinking water, etc. Therefore, it is necessary to prevent the transmission of enterovirus from the environment to people through drinking water intervention. Secondly, exposure to or use of heavily polluted water is associated with a risk of skin diseases. Excessive bacteria in seawater and heavy metals in drinking water are the main pathogenic factors of skin diseases. Thirdly, water pollution can pose health risks to humans through any of the three links: the source of water, the treatment of water, and the delivery of water. Arsenic, nitrate, chromium, and trihalomethane are major carcinogens in water sources. Carcinogens may be introduced during chlorine treatment from water treatment. The effects of drinking water pollution on cancer are complex, including chlorinated by-products, heavy metals, radionuclides, herbicides and pesticides left in water, etc., Finally, water pollution is an important cause of children’s diseases. Contact with microbiologically infected water can cause diarrhoeal disease in children. Malnutrition and weakened immunity from diarrhoeal diseases can lead to other diseases.

This study systematically analyzed the impact of water pollution on human health and the heterogeneity of diseases from the perspective of different diseases, focusing on a detailed review of the relationship, mechanism and influencing factors of water pollution and diseases. From the point of view of limitations, this paper mainly focuses on the research of environmental science and environmental management, and the research on pathology is less involved. Based on this, future research can strengthen research at medical and pathological levels.

In response to the above research conclusions, countries, especially developing countries, need to adopt corresponding water management policies to reduce the harm caused by water pollution to human health. Firstly, there is a focus on water quality at the point of use, with interventions to improve water quality, including chlorination and safe storage ( Gundry et al., 2004 ), and provision of treated and clean water ( Khan et al., 2013 ). Secondly, in order to reduce the impact of water pollution on skin diseases, countries should conduct epidemiological studies on their own in order to formulate health-friendly bathing water quality standards suitable for their specific conditions ( Cheung et al., 1990 ). Thirdly, in order to reduce the cancer caused by water pollution, the whole-process supervision of water quality should be strengthened, that is, the purity of water sources, the scientific nature of water treatment and the effectiveness of drinking water monitoring. Fourthly, each society should prevent and control source pollution from production, consumption, and transportation ( Landrigan et al., 2018 ). Fifthly, health education is widely carried out. Introduce environmental education, educate residents on sanitary water through newspapers, magazines, television, Internet and other media, and enhance public health awareness. Train farmers to avoid overuse of agricultural chemicals that contaminate drinking water.

Author Contributions

Conceptualization, XX|; methodology, LL; data curation, HY; writing and editing, LL; project administration, XX|.

This article is a phased achievement of The National Social Science Fund of China: Research on the blocking mechanism of the critical poor households returning to poverty due to illness, No: 20BJY057.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s Note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Afroz, R., Rahman, A., and Rahman, A. (2017). Health Impact of River Water Pollution in Malaysia. Int. J. Adv. Appl. Sci. 4 (5), 78–85. doi:10.21833/ijaas.2017.05.014

CrossRef Full Text | Google Scholar

Ahmed, S., and Ismail, S. (2018). Water Pollution and its Sources, Effects and Management: a Case Study of Delhi. Int. J. Curr. Adv. Res. 7 (2), 10436–10442. doi:10.24327/ijcar.2018.10442.1768

Ansari, Z. Z., and Akhmatov, S. V. (2020). Impacts of Water Pollution on Human Health: A Case Study of Delhi .

Google Scholar

Arif, A., Malik, M. F., Liaqat, S., Aslam, A., Mumtaz, K., and Afzal, A. (2020). 3. Water Pollution and Industries. Pure Appl. Biol. (PAB) 9 (4), 2214–2224. doi:10.19045/bspab.2020.90237

Arnold, B. F., and Colford, J. M. (2007). Treating Water with Chlorine at Point-Of-Use to Improve Water Quality and Reduce Child Diarrhea in Developing Countries: a Systematic Review and Meta-Analysis. Am. J. Trop. Med. Hyg. 76 (2), 354–364. doi:10.4269/ajtmh.2007.76.354

PubMed Abstract | CrossRef Full Text | Google Scholar

Bartlett, S. (2003). Water, Sanitation and Urban Children: the Need to Go beyond “Improved” Provision. Environ. Urbanization 15 (2), 57–70. doi:10.1177/095624780301500220

Bessong, P. O., Odiyo, J. O., Musekene, J. N., and Tessema, A. (2009). Spatial Distribution of Diarrhoea and Microbial Quality of Domestic Water during an Outbreak of Diarrhoea in the Tshikuwi Community in Venda, South Africa. J. Health Popul. Nutr. 27 (5), 652–659. doi:10.3329/jhpn.v27i5.3642

Boldo, E., MartÍN-Olmedo, P., Medina, S., Pirard, P., Mouly, D., and Beaudeau, P. (2006). Towards the Quantification of Health Impacts Caused by Drinking-Water Pollution in European Countries. Epidemiology 17 (6), S447. doi:10.1097/00001648-200611001-01198

Brown, J., and Clasen, T. (2012). High Adherence Is Necessary to Realize Health Gains from Water Quality Interventions. PLoS ONE 7 (5), e36735–9. doi:10.1371/journal.pone.0036735

Cantor, K. P., Hoover, R., Mason, T. J., and McCabe, L. J. (1978). Associations of Cancer Mortality with Halomethanes in Drinking Water. J. Natl. Cancer Inst. 61 (4), 979

PubMed Abstract | Google Scholar

Cantor, K. P. (1997). Drinking Water and Cancer. Cancer Causes Control CCC 8 (3), 292–308. doi:10.1023/a:1018444902486

Chen, B., Wang, M., Duan, M., Ma, X., Hong, J., Xie, F., et al. (2019). In Search of Key: Protecting Human Health and the Ecosystem from Water Pollution in China. J. Clean. Prod. 228, 101–111. doi:10.1016/j.jclepro.2019.04.228

Cheung, W. H. S., Chang, K. C. K., Hung, R. P. S., and Kleevens, J. W. L. (1990). Health Effects of Beach Water Pollution in Hong Kong. Epidemiol. Infect. 105 (1), 139–162. doi:10.1017/s0950268800047737

Cheung, W. H. S., Hung, R. P. S., Chang, K. C. K., and Kleevens, J. W. L. (1991). Epidemiological Study of Beach Water Pollution and Health-Related Bathing Water Standards in Hong Kong. Water Sci. Technol. 23 (1-3), 243–252. doi:10.2166/wst.1991.0422

Chowdhary, P., Bharagava, R. N., Mishra, S., and Khan, N. (2020). Role of Industries in Water Scarcity and its Adverse Effects on Environment and Human Health. Environ. Concerns Sustain. Dev. , 235–256. doi:10.1007/978-981-13-5889-0_12

Clasen, T. F., Alexander, K. T., Sinclair, D., Boisson, S., Peletz, R., Chang, H. H., et al. (2015). Interventions to Improve Water Quality for Preventing Diarrhoea. Cochrane Database Syst. Rev. 10, CD004794. doi:10.1002/14651858.CD004794.pub3

Clasen, T., Schmidt, W.-P., Rabie, T., Roberts, I., and Cairncross, S. (2007). Interventions to Improve Water Quality for Preventing Diarrhoea: Systematic Review and Meta-Analysis. Bmj 334 (7597), 782. doi:10.1136/bmj.39118.489931.be

Conroy, R. M., Elmore-Meegan, M., Joyce, T., McGuigan, K. G., and Barnes, J. (1996). Solar Disinfection of Drinking Water and Diarrhoea in Maasai Children: a Controlled Field Trial. Lancet 348 (9043), 1695–1697. doi:10.1016/s0140-6736(96)02309-4

Dasgupta, P. (2004). Valuing Health Damages from Water Pollution in Urban Delhi, India: a Health Production Function Approach. Envir. Dev. Econ. 9 (1), 83–106. doi:10.1017/s1355770x03001098

Dwivedi, S., Mishra, S., and Tripathi, R. D. (2018). Ganga Water Pollution: A Potential Health Threat to Inhabitants of Ganga Basin. Environ. Int. 117, 327–338. doi:10.1016/j.envint.2018.05.015

Ebenstein, A. (2012). The Consequences of Industrialization: Evidence from Water Pollution and Digestive Cancers in China. Rev. Econ. Statistics 94 (1), 186–201. doi:10.1162/rest_a_00150

El-Kowrany, S. I., El- Zamarany, E. A., El-Nouby, K. A., El-Mehy, D. A., Abo Ali, E. A., and Othman, A. A. (2016). Water Pollution in the Middle Nile Delta, Egypt: an Environmental Study. J. Adv. Res. 7 (5), 781–794. doi:10.1016/j.jare.2015.11.005

Enrique Biagini, R. (1975). Chronic Arsenic Water Pollution in the Republic of Argentina. Med. Cutan. Ibero Lat. Am. 3 (6), 423

Esrey, S. A., Potash, J. B., Roberts, L., and Shiff, C. (1991). Effects of Improved Water Supply and Sanitation on Ascariasis, Diarrhoea, Dracunculiasis, Hookworm Infection, Schistosomiasis, and Trachoma. Bull. World Health Organ 69 (5), 609

Ferreccio, C., González, C., Milosavjlevic, V., Marshall, G., Sancha, A. M., and Smith, A. H. (2000). Lung Cancer and Arsenic Concentrations in Drinking Water in Chile. Epidemiology 11 (6), 673–679. doi:10.1097/00001648-200011000-00010

Fewtrell, L., and Colford, J. M. (2005). Water, Sanitation and Hygiene in Developing Countries: Interventions and Diarrhoea-A Review. Water Sci. Technol. A J. Int. Assoc. Water Pollut. Res. 52 (8), 133–142. doi:10.2166/wst.2005.0244

Fitzgerald, E. F., Schell, L. M., Marshall, E. G., Carpenter, D. O., Suk, W. A., and Zejda, J. E. (1998). Environmental Pollution and Child Health in Central and Eastern Europe. Environ. Health Perspect. 106 (6), 307–311. doi:10.1289/ehp.98106307

Fleisher, J. M., and Kay, D. (2006). Risk Perception Bias, Self-Reporting of Illness, and the Validity of Reported Results in an Epidemiologic Study of Recreational Water Associated Illnesses. Mar. Pollut. Bull. 52 (3), 264–268. doi:10.1016/j.marpolbul.2005.08.019

Fong, T.-T., and Lipp, E. K. (2005). Enteric Viruses of Humans and Animals in Aquatic Environments: Health Risks, Detection, and Potential Water Quality Assessment Tools. Microbiol. Mol. Biol. Rev. 69 (2), 357–371. doi:10.1128/mmbr.69.2.357-371.2005

Froom, P. (2009). Water Pollution and Cancer in Israeli Navy Divers. Int. J. Occup. Environ. Health 15 (3), 326–328. doi:10.1179/oeh.2009.15.3.326

Gundry, S., Wright, J., and Conroy, R. (2004). A Systematic Review of the Health Outcomes Related to Household Water Quality in Developing Countries. J. water health 2 (1), 1–13. doi:10.2166/wh.2004.0001

Halder, J., Islam, N., and Islam, N. (2015). Water Pollution and its Impact on the Human Health. Eh 2 (1), 36–46. doi:10.15764/eh.2015.01005

Hanif, M., Miah, R., Islam, M., and Marzia, S. (2020). Impact of Kapotaksha River Water Pollution on Human Health and Environment. Prog. Agric. 31 (1), 1–9. doi:10.3329/pa.v31i1.48300

Haseena, M., Malik, M. F., Javed, A., Arshad, S., Asif, N., Zulfiqar, S., et al. (2017). Water Pollution and Human Health. Environ. Risk Assess. Remediat. 1 (3), 20. doi:10.4066/2529-8046.100020

Henry, F. J., Huttly, S. R. A., Patwary, Y., and Aziz, K. M. A. (1990). Environmental Sanitation, Food and Water Contamination and Diarrhoea in Rural Bangladesh. Epidemiol. Infect. 104 (2), 253–259. doi:10.1017/s0950268800059422

Jalan, J., and Ravallion, M. (2003). Does Piped Water Reduce Diarrhea for Children in Rural India? J. Econ. 112 (1), 153–173. doi:10.1016/s0304-4076(02)00158-6

Jensen, P. K., Jayasinghe, G., Hoek, W., Cairncross, S., and Dalsgaard, A. (2004). Is There an Association between Bacteriological Drinking Water Quality and Childhood Diarrhoea in Developing Countries? Trop. Med. Int. Health 9 (11), 1210–1215. doi:10.1111/j.1365-3156.2004.01329.x

Jorgenson, A. K. (2009). Foreign Direct Investment and the Environment, the Mitigating Influence of Institutional and Civil Society Factors, and Relationships between Industrial Pollution and Human Health. Organ. Environ. 22 (2), 135–157. doi:10.1177/1086026609338163

Kaur, G., Kumar, R., Mittal, S., Sahoo, P. K., and Vaid, U. (2021). Ground/drinking Water Contaminants and Cancer Incidence: A Case Study of Rural Areas of South West Punjab, India. Hum. Ecol. Risk Assess. Int. J. 27 (1), 205–226. doi:10.1080/10807039.2019.1705145

Kazi, T. G., Arain, M. B., Baig, J. A., Jamali, M. K., Afridi, H. I., Jalbani, N., et al. (2009). The Correlation of Arsenic Levels in Drinking Water with the Biological Samples of Skin Disorders. Sci. Total Environ. 407 (3), 1019–1026. doi:10.1016/j.scitotenv.2008.10.013

Khan, S., Shahnaz, M., Jehan, N., Rehman, S., Shah, M. T., and Din, I. (2013). Drinking Water Quality and Human Health Risk in Charsadda District, Pakistan. J. Clean. Prod. 60, 93–101. doi:10.1016/j.jclepro.2012.02.016

Kochhar, N., Gill, G. S., Tuli, N., Dadwal, V., and Balaram, V. (2007). Chemical Quality of Ground Water in Relation to Incidence of Cancer in Parts of SW Punjab, India. Asian J. Water, Environ. Pollut. 4 (2), 107 doi:10.1086/114154

Kumar, S., Meena, H. M., and Verma, K. (2017). Water Pollution in India: its Impact on the Human Health: Causes and Remedies. Int. J. Appl. Environ. Sci. 12 (2), 275

Lai, W. (2017). Pesticide Use and Health Outcomes: Evidence from Agricultural Water Pollution in China. J. Environ. Econ. Manag. 86, 93–120. doi:10.1016/j.jeem.2017.05.006

Landrigan, P. J., Fuller, R., Fisher, S., Suk, W. A., Sly, P., Chiles, T. C., et al. (2018). Pollution and Children's Health. Sci. Total Environ. 650 (Pt 2), 2389–2394. doi:10.1016/j.scitotenv.2018.09.375

Lin, H.-J., Sung, T.-I., Chen, C.-Y., and Guo, H.-R. (2013). Arsenic Levels in Drinking Water and Mortality of Liver Cancer in Taiwan. J. Hazard. Mater. 262, 1132–1138. doi:10.1016/j.jhazmat.2012.12.049

Lu, Y., Song, S., Wang, R., Liu, Z., Meng, J., Sweetman, A. J., et al. (2015). Impacts of Soil and Water Pollution on Food Safety and Health Risks in China. Environ. Int. 77, 5–15. doi:10.1016/j.envint.2014.12.010

Marino, D. D. (2007). Water and Food Safety in the Developing World: Global Implications for Health and Nutrition of Infants and Young Children. J. Am. Dietetic Assoc. 107 (11), 1930–1934. doi:10.1016/j.jada.2007.08.013

Marmot, M., Atinmo, T., Byers, T., Chen, J., and Zeisel, S. H. (2007). Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. Nutr. Bull.

Marr, A., and Dasgupta, N. (2009). Industrial Water Pollution in Dhaka, Bangladesh: Strategies and Incentives for Pollution Control in Small and Medium Enterprises. Int. J. Interdiscip. Soc. Sci. Annu. Rev. 3 (11), 97–108. doi:10.18848/1833-1882/cgp/v03i11/52752

Morris, R. D. (1995). Drinking Water and Cancer. Environ. Health Perspect. 103, 225. doi:10.2307/3432315

Moss, B. (2008). Water Pollution by Agriculture. Phil. Trans. R. Soc. B 363 (1491), 659–666. doi:10.1098/rstb.2007.2176

Page, T., Harris, R. H., and Epstein, S. S. (1976). Drinking Water and Cancer Mortality in Louisiana. Science 193 (4247), 55–57. doi:10.1126/science.935854

Pandey, S. (2006). Water Pollution and Health. Kathmandu Univ. Med. J. (KUMJ) 4 (1), 128. doi:10.1016/j.crvi.2013.04.013

Parris, K. (2011). Impact of Agriculture on Water Pollution in OECD Countries: Recent Trends and Future Prospects. Int. J. Water Resour. Dev. 27 (1), 33–52. doi:10.1080/07900627.2010.531898

Payment, P., Siemiatycki, J., Richardson, L., Renaud, G., Franco, E., and Prevost, M. (1997). A Prospective Epidemiological Study of Gastrointestinal Health Effects Due to the Consumption of Drinking Water. Int. J. Environ. Health Res. 7 (1), 5–31. doi:10.1080/09603129773977

Rabbani, M., Chowdhury, M., and Khan, N. A. (2010). Impacts of Industrial Pollution on Human Health: Empirical Evidences from an Industrial Hotspot (Kaliakoir) in Bangladesh. Asian J. Water, Environ. Pollut. 7 (1), 27

Rajal, V. B., Cruz, C., and Last, J. A. (2010). Water Quality Issues and Infant Diarrhoea in a South American Province. Glob. Public Health 5 (4), 348–363. doi:10.1080/17441690802447267

Rampen, F. H. J., Nelemans, P. J., and Verbeek, A. L. (1992). Is Water Pollution a Cause of Cutaneous Melanoma? Epidemiology 3, 263–265. doi:10.1097/00001648-199205000-00013

Royal Commission for Environmental Pollution 1979 Seventh Report. Agriculture and Pollution . London, UK: H.M.S.O .

Rusiñol, M., Fernandez-Cassi, X., Timoneda, N., Carratalà, A., and Abril, J. F. (2015). Evidence of Viral Dissemination and Seasonality in a Mediterranean River Catchment: Implications for Water Pollution Management. J. Environ. Manag. 159, 58–67. doi:10.1016/j.jenvman.2015.05.019

Schullehner, J., Hansen, B., Thygesen, M., Pedersen, C. B., and Sigsgaard, T. (2018). Nitrate in Drinking Water and Colorectal Cancer Risk: A Nationwide Population-Based Cohort Study. Int. J. Cancer 143 (1), 73–79. doi:10.1002/ijc.31306

Schwarzenbach, R. P., Egli, T., Hofstetter, T. B., Von Gunten, U., and Wehrli, B. (2010). Global Water Pollution and Human Health. Annu. Rev. Environ. Resour. 35, 109–136. doi:10.1146/annurev-environ-100809-125342

Sliman, N. A. (1978). Outbreak of Guillain-Barre Syndrome Associated with Water Pollution. Bmj 1 (6115), 751–752. doi:10.1136/bmj.1.6115.751

Smith, A. H., Hopenhayn-Rich, C., Bates, M. N., Goeden, H. M., Hertz-Picciotto, I., Duggan, H. M., et al. (1992). Cancer Risks from Arsenic in Drinking Water. Environ. Health Perspect. 97, 259–267. doi:10.1289/ehp.9297259

Stephens, J. K. (2002). Deterioration of Stored Domestic Water Quality and Diarrhoea in Zenu . University of Ghana .

Stevenson, A. H. (1953). Studies of Bathing Water Quality and Health. Am. J. Public Health Nations Health 43 (5 Pt 1), 529–538. doi:10.2105/ajph.43.5_pt_1.529

Team, S. H. (2004). Water, Sanitation and Hygiene Links to Health: Facts and Figures . World Health Organization .

Tondel, M., Rahman, M., Magnuson, A., Chowdhury, I. A., Faruquee, M. H., and Ahmad, S. A. (1999). The Relationship of Arsenic Levels in Drinking Water and the Prevalence Rate of Skin Lesions in Bangladesh. Environ. health Perspect. 107 (9), 727–729. doi:10.1289/ehp.99107727

Tseng, C.-H., Lei, C., and Chen, Y.-C. (2018). Evaluating the Health Costs of Oral Hexavalent Chromium Exposure from Water Pollution: A Case Study in Taiwan. J. Clean. Prod. 172, 819–826. doi:10.1016/j.jclepro.2017.10.177

Ustaoğlu, F., Tepe, Y., Taş, B., and Pag, N. (2020). Assessment of Stream Quality and Health Risk in a Subtropical Turkey River System: A Combined Approach Using Statistical Analysis and Water Quality Index. Ecol. Indic. , 113. doi:10.1016/j.ecolind.2019.105815

Vartiainen, T., Pukkala, E., Rienoja, T., Strandman, T., and Kaksonen, K. (1993). Population Exposure to Tri- and Tetrachloroethene and Cancer Risk: Two Cases of Drinking Water Pollution. Chemosphere 27 (7), 1171–1181. doi:10.1016/0045-6535(93)90165-2

Victora, C. G., Smith, P. G., Vaughan, J. P., Nobre, L. C., Lombard, C., Teixeira, A. M. B., et al. (1988). Water Supply, Sanitation and Housing in Relation to the Risk of Infant Mortality from Diarrhoea. Int. J. Epidemiol. 17 (3), 651–654. doi:10.1093/ije/17.3.651

Vladeva, S., Gatseva, P., and Gopina, G. (2000). Comparative Analysis of Results from Studies of Goitre in Children from Bulgarian Villages with Nitrate Pollution of Drinking Water in 1995 and 1998. Cent. Eur. J. Public Health 8 (3), 179

Waddington, H., Snilstveit, B., White, H., and Fewtrell, L. (2009). Water, Sanitation and Hygiene Interventions to Combat Childhood Diarrhoea in Developing Countries . New Delhi India Global Development Network International Initiative for Impact Evaluation Aug .

Witkowski, K. M., and Johnson, N. E. (1992). Organic-solvent Water Pollution and Low Birth Weight in Michigan. Soc. Biol. 39 (1-2), 45–54. doi:10.1080/19485565.1992.9988803

Wu, C., Maurer, C., Wang, Y., Xue, S., and Davis, D. L. (1999). Water Pollution and Human Health in China. Environ. Health Perspect. 107 (4), 251–256. doi:10.1289/ehp.99107251

Wu, H., Gai, Z., Guo, Y., Li, Y., Hao, Y., and Lu, Z. N. (2020). Does Environmental Pollution Inhibit Urbanization in China? A New Perspective through Residents' Medical and Health Costs. Environ. Res. 182 (Mar.), 109128–109128.9. doi:10.1016/j.envres.2020.109128

Xiao, J., Wang, L., Deng, L., and Jin, Z. (2019). Characteristics, Sources, Water Quality and Health Risk Assessment of Trace Elements in River Water and Well Water in the Chinese Loess Plateau. Sci. Total Environ. 650 (Pt 2), 2004–2012. doi:10.1016/j.scitotenv.2018.09.322

Xu, C., Xing, D., Wang, J., and Xiao, G. (2019). The Lag Effect of Water Pollution on the Mortality Rate for Esophageal Cancer in a Rapidly Industrialized Region in China. Environ. Sci. Pollut. Res. 26 (32), 32852–32858. doi:10.1007/s11356-019-06408-z

Xu, X., Wang, Q., and Li, C. (2022b). The Impact of Dependency Burden on Urban Household Health Expenditure and its Regional Heterogeneity in China: Based on Quantile Regression Method. Front. Public Health 10, 876088. doi:10.3389/fpubh.2022.876088

Xu, X., Yang, H., and Li, C. (2022a). Theoretical Model and Actual Characteristics of Air Pollution Affecting Health Cost: A Review. Ijerph 19, 3532. doi:10.3390/ijerph19063532

Yassin, M. M., Amr, S. S. A., and Al-Najar, H. M. (2006). Assessment of Microbiological Water Quality and its Relation to Human Health in Gaza Governorate, Gaza Strip. Public Health 120 (12), 1177. doi:10.1016/j.puhe.2006.07.026

Yau, V., Wade, T. J., de Wilde, C. K., and Colford, J. M. (2009). Skin-related Symptoms Following Exposure to Recreational Water: a Systematic Review and Meta-Analysis. Water Expo. Health 1 (2), 79–103. doi:10.1007/s12403-009-0012-9

Zaveri, E. D., Russ, J. D., Desbureaux, S. G., Damania, R., Rodella, A. S., and Ribeiro Paiva De Souza, G. (20203). The Nitrogen Legacy: The Long-Term Effects of Water Pollution on Human Capital . World Bank Policy Research Working Paper .

Zhang, X.-L., Bing, Z., Xing, Z., Chen, Z.-F., Zhang, J.-Z., Liang, S.-Y., et al. (2003). Research and Control of Well Water Pollution in High Esophageal Cancer Areas. Wjg 9 (6), 1187–1190. doi:10.3748/wjg.v9.i6.1187

Zhitkovich, A. (2011). Chromium in Drinking Water: Sources, Metabolism, and Cancer Risks. Chem. Res. Toxicol. 24 (10), 1617–1629. doi:10.1021/tx200251t

Keywords: water pollution, human health, disease heterogeneity, water intervention, health cost

Citation: Lin L, Yang H and Xu X (2022) Effects of Water Pollution on Human Health and Disease Heterogeneity: A Review. Front. Environ. Sci. 10:880246. doi: 10.3389/fenvs.2022.880246

Received: 21 February 2022; Accepted: 09 June 2022; Published: 30 June 2022.

Reviewed by:

Copyright © 2022 Lin, Yang and Xu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Xiaocang Xu, [email protected]

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Ground Water Vulnerability Assessment: Predicting Relative Contamination Potential Under Conditions of Uncertainty (1993)

Chapter: 5 case studies, 5 case studies, introduction.

This chapter presents six case studies of uses of different methods to assess ground water vulnerability to contamination. These case examples demonstrate the wide range of applications for which ground water vulnerability assessments are being conducted in the United States. While each application presented here is directed toward the broad goal of protecting ground water, each is unique in its particular management requirements. The intended use of the assessment, the types of data available, the scale of the assessments, the required resolution, the physical setting, and institutional factors all led to very different vulnerability assessment approaches. In only one of the cases presented here, Hawaii, are attempts made to quantify the uncertainty associated with the assessment results.

Introduction

Ground water contamination became an important political and environmental issue in Iowa in the mid-1980s. Research reports, news headlines, and public debates noted the increasing incidence of contaminants in rural and urban well waters. The Iowa Ground water Protection Strategy (Hoyer et al. 1987) indicated that levels of nitrate in both private and municipal

wells were increasing. More than 25 percent of the state's population was served by water with concentrations of nitrate above 22 milligrams per liter (as NO 3 ). Similar increases were noted in detections of pesticides in public water supplies; about 27 percent of the population was periodically consuming low concentrations of pesticides in their drinking water. The situation in private wells which tend to be shallower than public wells may have been even worse.

Defining the Question

Most prominent among the sources of ground water contamination were fertilizers and pesticides used in agriculture. Other sources included urban use of lawn chemicals, industrial discharges, and landfills. The pathways of ground water contamination were disputed. Some interests argued that contamination occurs only when a natural or human generated condition, such as sinkholes or agricultural drainage wells, provides preferential flow to underground aquifers, resulting in local contamination. Others suggested that chemicals applied routinely to large areas infiltrate through the vadose zone, leading to widespread aquifer contamination.

Mandate, Selection, and Implementation

In response to growing public concern, the state legislature passed the Iowa Ground water Protection Act in 1987. This landmark statute established the policy that further contamination should be prevented to the "maximum extent practical" and directed state agencies to launch multiyear programs of research and education to characterize the problem and identify potential solutions.

The act mandated that the Iowa Department of Natural Resources (DNR) assess the vulnerability of the state's ground water resources to contamination. In 1991, DNR released Ground water Vulnerability Regions of Iowa , a map developed specifically to depict the intrinsic susceptibility of ground water resources to contamination by surface or near-surface activities. This assessment had three very limited purposes: (1) to describe the physical setting of ground water resources in the state, (2) to educate policy makers and the public about the potential for ground water contamination, and (3) to provide guidance for planning and assigning priorities to ground water protection efforts in the state.

Unlike other vulnerability assessments, the one in Iowa took account of factors that affect both ground water recharge and well development. Ground water recharge involves issues related to aquifer contamination; well development involves issues related to contamination of water supplies in areas where sources other than bedrock aquifers are used for drinking water. This

approach considers jointly the potential impacts of contamination on the water resource in aquifers and on the users of ground water sources.

The basic principle of the Iowa vulnerability assessment involves the travel time of water from the land surface to a well or an aquifer. When the time is relatively short (days to decades), vulnerability is considered high. If recharge occurs over relatively long periods (centuries to millennia), vulnerability is low. Travel times were determined by evaluating existing contaminants and using various radiometric dating techniques. The large reliance on travel time in the Iowa assessment likely results in underestimation of the potential for eventual contamination of the aquifer over time.

The most important factor used in the assessment was thickness of overlying materials which provide natural protection to a well or an aquifer. Other factors considered included type of aquifer, natural water quality in an aquifer, patterns of well location and construction, and documented occurrences of well contamination. The resulting vulnerability map ( Plate 1 ) delineates regions having similar combinations of physical characteristics that affect ground water recharge and well development. Qualitative ratings are assigned to the contamination potential for aquifers and wells for various types and locations of water sources. For example, the contamination potential for wells in alluvial aquifers is considered high, while the potential for contamination of a variable bedrock aquifer protected by moderate drift or shale is considered low.

Although more sophisticated approaches were investigated for use in the assessment, ultimately no complex process models of contaminant transport were used and no distinction was made among Iowa's different soil types. The DNR staff suggested that since the soil cover in most of the state is such a small part of the overall aquifer or well cover, processes that take place in those first few inches are relatively similar and, therefore, insignificant in terms of relative susceptibilities to ground water contamination. The results of the vulnerability assessment followed directly from the method's assumptions and underlying principles. In general, the thicker the overlay of clayey glacial drift or shale, the less susceptible are wells or aquifers to contamination. Where overlying materials are thin or sandy, aquifer and well susceptibilities increase. Vulnerability is also greater in areas where sinkholes or agricultural drainage wells allow surface and tile water to bypass natural protective layers of soil and rapidly recharge bedrock aquifers.

Basic data on geologic patterns in the state were extrapolated to determine the potential for contamination. These data were supplemented by databases on water contamination (including the Statewide Rural Well-Water Survey conducted in 1989-1990) and by research insights into the transport, distribution, and fate of contaminants in ground water. Some of the simplest data needed for the assessment were unavailable. Depth-to-bedrock information had never been developed, so surface and bedrock topographic

maps were revised and integrated to create a new statewide depth-to-bedrock map. In addition, information from throughout the state was compiled to produce the first statewide alluvial aquifer map. All new maps were checked against available well-log data, topographic maps, outcrop records, and soil survey reports to assure the greatest confidence in this information.

While the DNR was working on the assessment, it was also asked to integrate various types of natural resource data into a new computerized geographic information system (GIS). This coincident activity became a significant contributor to the assessment project. The GIS permitted easier construction of the vulnerability map and clearer display of spatial information. Further, counties or regions in the state can use the DNR geographic data and the GIS to explore additional vulnerability parameters and examine particular areas more closely to the extent that the resolution of the data permits.

The Iowa vulnerability map was designed to provide general guidance in planning and ranking activities for preventing contamination of aquifers and wells. It is not intended to answer site-specific questions, cannot predict contaminant concentrations, and does not even rank the different areas of the state by risk of contamination. Each of these additional uses would require specific assessments of vulnerability to different activities, contaminants, and risk. The map is simply a way to communicate qualitative susceptibility to contamination from the surface, based on the depth and type of cover, natural quality of the aquifer, well location and construction, and presence of special features that may alter the transport of contaminants.

Iowa's vulnerability map is viewed as an intermediate product in an ongoing process of learning more about the natural ground water system and the effects of surface and near-surface activities on that system. New maps will contain some of the basic data generated by the vulnerability study. New research and data collection will aim to identify ground water sources not included in the analysis (e.g., buried channel aquifers and the "salt and pepper sands" of western Iowa). Further analyses of existing and new well water quality data will be used to clarify relationships between aquifer depth and ground water contamination. As new information is obtained, databases and the GIS will be updated. Over time, new vulnerability maps may be produced to reflect new data or improved knowledge of environmental processes.

The Cape Cod sand and gravel aquifer is the U.S. Environmental Protection Agency (EPA) designated sole source of drinking water for Barnstable County, Massachusetts (ca. 400 square miles, winter population 186,605 in 1990, summer population ca. 500,000) as well as the source of fresh water for numerous kettle hole ponds and marine embayments. During the past 20 years, a period of intense development of open land accompanied by well-reported ground water contamination incidents, Cape Cod has been the site of intensive efforts in ground water management and analysis by many organizations, including the Association for the Preservation of Cape Cod, the U.S. Geological Survey, the Massachusetts Department of Environmental Protection (formerly the Department of Environmental Quality Engineering), EPA, and the Cape Cod Commission (formerly the Cape Cod Planning and Economic Development Commission). An earlier NRC publication, Ground Water Quality Protection: State and Local Strategies (1986) summarizes the Cape Cod ground water protection program.

The Area Wide Water Quality Management Plan for Cape Cod (CCPEDC 1978a, b), prepared in response to section 208 of the federal Clean Water Act, established a management strategy for the Cape Cod aquifer. The plan emphasized wellhead protection of public water supplies, limited use of public sewage collection systems and treatment facilities, and continued general reliance on on-site septic systems, and relied on density controls for regulation of nitrate concentrations in public drinking water supplies. The water quality management planning program began an effort to delineate the zones of contribution (often called contributing areas) for public wells on Cape Cod that has become increasingly sophisticated over the years. The effort has grown to address a range of ground water resources and ground water dependent resources beyond the wellhead protection area, including fresh and marine surface waters, impaired areas, and water quality improvement areas (CCC 1991). Plate 2 depicts the water resources classifications for Cape Cod.

Selection and Implementation of Approaches

The first effort to delineate the contributing area to a public water supply well on Cape Cod came in 1976 as part of the initial background studies for the Draft Area Wide Water Quality Management Plan for Cape

Cod (CCPEDC 1978a). This effort used a simple mass balance ratio of a well's pumping volume to an equal volume average annual recharge evenly spread over a circular area. This approach, which neglects any hydrogeologic characteristics of the aquifer, results in a number of circles of varying radii that are centered at the wells.

The most significant milestone in advancing aquifer protection was the completion of a regional, 10 foot contour interval, water table map of the county by the USGS (LeBlanc and Guswa 1977). By the time that the Draft and Final Area Wide Water Quality Management Plans were published (CCPEDC 1978a, b), an updated method for delineating zones of contribution, using the regional water table map, had been developed. This method used the same mass balance approach to characterize a circle, but also extended the zone area by 150 percent of the circle's radius in the upgradient direction. In addition, a water quality watch area extending upgradient from the zone to the ground water divide was recommended. Although this approach used the regional water table map for information on ground water flow direction, it still neglected the aquifer's hydrogeologic parameters.

In 1981, the USGS published a digital model of the aquifer that included regional estimates of transmissivity (Guswa and LeBlanc 1981). In 1982, the CCPEDC used a simple analytical hydraulic model to describe downgradient and lateral capture limits of a well in a uniform flow field (Horsley 1983). The input parameters required for this model included hydraulic gradient data from the regional water table map and transmissivity data from the USGS digital model. The downgradient and lateral control points were determined using this method, but the area of the zone was again determined by the mass balance method. Use of the combined hydraulic and mass balance method resulted in elliptical zones of contribution that did not extend upgradient to the ground water divide. This combined approach attempted to address three-dimensional ground water flow beneath a partially penetrating pumping well in a simple manner.

At about the same time, the Massachusetts Department of Environmental Protection started the Aquifer Lands Acquisition (ALA) Program to protect land within zones of contribution that would be delineated by detailed site-specific studies. Because simple models could not address three-dimensional flow and for several other reasons, the ALA program adopted a policy that wellhead protection areas or Zone IIs (DEP-WS 1991) should be extended upgradient all the way to a ground water divide. Under this program, wells would be pump tested for site-specific aquifer parameters and more detailed water table mapping would often be required. In many cases, the capture area has been delineated by the same simple hydraulic analytical model but the zone has been extended to the divide. This method has resulted in some 1989 zones that are 3,000 feet wide and extend 4.5

miles upgradient, still without a satisfactory representation of three-dimensional flow to the well.

Most recently the USGS (Barlow 1993) has completed a detailed subregional, particle-tracking three-dimensional ground water flow model that shows the complex nature of ground water flow to wells. This approach has shown that earlier methods, in general, overestimate the area of zones of contribution (see Figure 5.1 ).

In 1988, the public agencies named above completed the Cape Cod Aquifer Management Project (CCAMP), a resource-based ground water protection study that used two towns, Barnstable and Eastham, to represent the more and less urbanized parts of Cape Cod. Among the CCAMP products were a GIS-based assessment of potential for contamination as a result of permissible land use changes in the Barnstable zones of contribution (Olimpio et al. 1991) and a ground water vulnerability assessment by Heath (1988) using DRASTIC for the same area. Olimpio et al. characterized land uses by ranking potential contaminant sources without regard to differences in vulnerability within the zones. Heath's DRASTIC analysis of the same area, shown in Figure 5.2 , delineated two distinct zones of vulnerability based on hydrogeologic setting. The Sandwich Moraine setting, with deposits of silt, sand and gravel, and depths to ground water ranging from 0 to more than 125 feet, had DRASTIC values of 140 to 185; the Barnstable Outwash Plain, with permeable sand and fine gravel deposits with beds of silt and clay and depths to ground water of less than 50 feet, yielded values of 185 to 210. The DRASTIC scores and relative contributions of the factors are shown in Tables 5.1 and 5.2 . Heath concluded that similar areas of Cape Cod would produce similar moderate to high vulnerability DRASTIC scores. The CCAMP project also addressed the potential for contamination of public water supply wells from new land uses allowable under existing zoning for the same area. The results of that effort are shown in Plate 4 .

In summary, circle zones were used initially when the hydrogeologic nature of the aquifer or of hydraulic flow to wells was little understood. The zones improved with an understanding of ground water flow and aquifer characteristics, but in recognition of the limitations of regional data, grossly conservative assumptions came into use. Currently, a truer delineation of a zone of contribution can be prepared for a given scenario using sophisticated models and highly detailed aquifer characterization. However, the area of a given zone still is highly dependent on the initial assumptions that dictate how much and in what circumstances a well is pumped. In the absence of ability to specify such conditions, conservative assumptions,

FIGURE 5.1 Contributing areas of wells and ponds in the complex flow system determined by using the three-dimensional model with 1987 average daily pumping rates. (Barlow 1993)

such as maximum prolonged pumping, prevail, and, therefore, conservatively large zones of contribution continue to be used for wellhead protection.

The ground water management experience of Cape Cod has resulted in a better understanding of the resource and the complexity of the aquifer

FIGURE 5.2 DRASTIC contours for Zone 1, Barnstable-Yarmouth, Massachusetts.

system, as well as the development of a more ambitious agenda for resource protection. Beginning with goals of protection of existing public water supplies, management interests have grown to include the protection of private wells, potential public supplies, fresh water ponds, and marine embayments. Public concerns over ground water quality have remained high and were a major factor in the creation of the Cape Cod Commission by the Massachusetts legislature. The commission is a land use planning and regulatory agency with broad authority over development projects and the ability to create special resource management areas. The net result of 20 years of effort by many individuals and agencies is the application of

TABLE 5.1 Ranges, Rating, and Weights for DRASTIC Study of Barnstable Outwash Plain Setting (NOTE: gpd/ft 2 = gallons per day per square foot) (Heath 1988)

TABLE 5.2 Ranges, Rating, and Weights for DRASTIC Study of Sandwich Moraine Setting (NOTE: gpd/ft 2 = gallons per day per square foot) (Heath 1988)

higher protection standards to broader areas of the Cape Cod aquifer. With some exceptions for already impaired areas, a differentiated resource protection approach in the vulnerable aquifer setting of Cape Cod has resulted in a program that approaches universal ground water protection.

Florida has 13 million residents and is the fourth most populous state (U.S. Bureau of the Census 1991). Like several other sunbelt states, Florida's population is growing steadily, at about 1,000 persons per day, and is estimated to reach 17 million by the year 2000. Tourism is the biggest industry in Florida, attracting nearly 40 million visitors each year. Ground water is the source of drinking water for about 95 percent of Florida's population; total withdrawals amount to about 1.5 billion gallons per day. An additional 3 billion gallons of ground water per day are pumped to meet the needs of agriculture—a $5 billion per year industry, second only to tourism in the state. Of the 50 states, Florida ranks eighth in withdrawal of fresh ground water for all purposes, second for public supply, first for rural domestic and livestock use, third for industrial/commercial use, and ninth for irrigation withdrawals.

Most areas in Florida have abundant ground water of good quality, but the major aquifers are vulnerable to contamination from a variety of land use activities. Overpumping of ground water to meet the growing demands of the urban centers, which accounts for about 80 percent of the state's population, contributes to salt water intrusion in coastal areas. This overpumping is considered the most significant problem for degradation of ground water quality in the state. Other major sources of ground water contaminants include: (1) pesticides and fertilizers (about 2 million tons/year) used in agriculture, (2) about 2 million on-site septic tanks, (3) more than 20,000 recharge wells used for disposing of stormwater, treated domestic wastewater, and cooling water, (4) nearly 6,000 surface impoundments, averaging one per 30 square kilometers, and (5) phosphate mining activities that are estimated to disturb about 3,000 hectares each year.

The Hydrogeologic Setting

The entire state is in the Coastal Plain physiographic province, which has generally low relief. Much of the state is underlain by the Floridan aquifer system, largely a limestone and dolomite aquifer that is found in both confined and unconfined conditions. The Floridan is overlain through most of the state by an intermediate aquifer system, consisting of predominantly clays and sands, and a surficial aquifer system, consisting of predominantly sands, limestone, and dolomite. The Floridan is one of the most productive aquifers in the world and is the most important source of drinking water for Florida residents. The Biscayne, an unconfined, shallow, limestone aquifer located in southeast Florida, is the most intensively used

aquifer and the sole source of drinking water for nearly 3 million residents in the Miami-Palm Beach coastal area. Other surficial aquifers in southern Florida and in the western panhandle region also serve as sources of ground water.

Aquifers in Florida are overlain by layers of sand, clay, marl, and limestone whose thickness may vary considerably. For example, the thickness of layers above the Floridan aquifer range from a few meters in parts of west-central and northern Florida to several hundred meters in south-central Florida and in the extreme western panhandle of the state. Four major groups of soils (designated as soil orders under the U.S. Soil Taxonomy) occur extensively in Florida. Soils in the western highlands are dominated by well-drained sandy and loamy soils and by sandy soils with loamy subsoils; these are classified as Ultisols and Entisols. In the central ridge of the Florida peninsula, are found deep, well-drained, sandy soils (Entisols) as well as sandy soils underlain by loamy subsoils or phosphatic limestone (Alfisols and Ultisols). Poorly drained sandy soils with organic-rich and clay-rich subsoils, classified as Spodosols, occur in the Florida flatwoods. Organic-rich muck soils (Histosols) underlain by muck or limestone are found primarily in an area extending south of Lake Okeechobee.

Rainfall is the primary source of ground water in Florida. Annual rainfall in the state ranges from 100 to 160 cm/year, averaging 125 cm/year, with considerable spatial (both local and regional) and seasonal variations in rainfall amounts and patterns. Evapotranspiration (ET) represents the largest loss of water; ET ranges from about 70 to 130 cm/year, accounting for between 50 and 100 percent of the average annual rainfall. Surface runoff and ground water discharge to streams averages about 30 cm/year. Annual recharge to surficial aquifers ranges from near zero in perennially wet, lowland areas to as much as 50 cm/year in well-drained areas; however, only a fraction of this water recharges the underlying Floridan aquifer. Estimates of recharge to the Floridan aquifer vary from less than 3 cm/year to more than 25 cm/year, depending on such factors as weather patterns (e.g., rainfall-ET balance), depth to water table, soil permeability, land use, and local hydrogeology.

Permeable soils, high net recharge rates, intensively managed irrigated agriculture, and growing demands from urban population centers all pose considerable threat of ground water contamination. Thus, protection of this valuable natural resource while not placing unreasonable constraints on agricultural production and urban development is the central focus of environmental regulation and growth management in Florida.

Along with California, Florida has played a leading role in the United

States in development and enforcement of state regulations for environmental protection. Detection in 1983 of aldicarb and ethylene dibromide, two nematocides used widely in Florida's citrus groves, crystallized the growing concerns over ground water contamination and the need to protect this vital natural resource. In 1983, the Florida legislature passed the Water Quality Assurance Act, and in 1984 adopted the State and Regional Planning Act. These and subsequent legislative actions provide the legal basis and guidance for the Ground Water Strategy developed by the Florida Department of Environmental Regulation (DER).

Ground water protection programs in Florida are implemented at federal, state, regional, and local levels and involve both regulatory and nonregulatory approaches. The most significant nonregulatory effort involves more than 30 ground water studies being conducted in collaboration with the Water Resources Division of the U.S. Geological Survey. At the state level, Florida statutes and administrative codes form the basis for regulatory actions. Although DER is the primary agency responsible for rules and statutes designed to protect ground water, the following state agencies participate to varying degrees in their implementation: five water management districts, the Florida Geological Survey, the Department of Health and Rehabilitative Services (HRS), the Department of Natural Resources, and the Florida Department of Agriculture and Consumer Services (DACS). In addition, certain interagency committees help coordinate the development and implementation of environmental codes in the state. A prominent example is the Pesticide Review Council which offers guidance to the DACS in developing pesticide use regulation. A method for screening pesticides in terms of their chronic toxicity and environmental behavior has been developed through collaborative efforts of the DACS, the DER, and the HRS (Britt et al. 1992). This method will be used to grant registration for pesticide use in Florida or to seek additional site-specific field data.

Selecting an Approach

The emphasis of the DER ground water program has shifted in recent years from primarily enforcement activity to a technically based, quantifiable, planned approach for resource protection.

The administrative philosophy for ground water protection programs in Florida is guided by the following principles:

Ground water is a renewable resource, necessitating a balance between withdrawals and natural or artificial recharge.

Ground water contamination should be prevented to the maximum degree possible because cleanup of contaminated aquifers is technically or economically infeasible.

It is impractical, perhaps unnecessary, to require nondegradation standards for all ground water in all locations and at all times.

The principle of ''most beneficial use" is to be used in classifying ground water into four classes on the basis of present quality, with the goal of attaining the highest level protection of potable water supplies (Class I aquifers).

Part of the 1983 Water Quality Assurance Act requires Florida DER to "establish a ground water quality monitoring network designed to detect and predict contamination of the State's ground water resources" via collaborative efforts with other state and federal agencies. The three basic goals of the ground water quality monitoring program are to:

Establish the baseline water quality of major aquifer systems in the state,

Detect and predict changes in ground water quality resulting from the effects of various land use activities and potential sources of contamination, and

Disseminate to local governments and the public, water quality data generated by the network.

The ground water monitoring network established by DER to meet the goals stated above consists of two major subnetworks and one survey (Maddox and Spicola 1991). Approximately 1,700 wells that tap all major potable aquifers in the state form the Background Network, which was designed to help define the background water quality. The Very Intensively Studied Area (VISA) network was established to monitor specific areas of the state considered highly vulnerable to contamination; predominant land use and hydrogeology were the primary attributes used to evaluate vulnerability. The DRASTIC index, developed by EPA, served as the basis for statewide maps depicting ground water vulnerability. Data from the VISA wells will be compared to like parameters sampled from Background Network wells in the same aquifer segment. The final element of the monitoring network is the Private Well Survey, in which up to 70 private wells per county will be sampled. The sampling frequency and chemical parameters to be monitored at each site are based on several factors, including network well classification, land use activities, hydrogeologic sensitivity, and funding. In Figure 5.3 , the principal aquifers in Florida are shown along with the distribution of the locations of the monitoring wells in the Florida DER network.

The Preservation 2000 Act, enacted in 1990, mandated that the Land Acquisition Advisory Council (LAAC) "provide for assessing the importance

FIGURE 5.3 Principal aquifers in Florida and the network of sample wells as of March 1990 (1642 wells sampled). (Adapted from Maddox and Spicola 1991, and Maddox et al. 1993.)

of acquiring lands which can serve to protect or recharge ground water, and the degree to which state land acquisition programs should focus on purchasing such land." The Ground Water Resources Committee, a subcommittee of the LAAC, produced a map depicting areas of ground water significance at regional scale (1:500,000) (see Figure 5.4 ) to give decision makers the basis for considering ground water as a factor in land acquisition under the Preservation 2000 Act (LAAC 1991). In developing maps for their districts, each of the five water management districts (WMDs) used the following criteria: ground water recharge, ground water quality, aquifer vulnerability, ground water availability, influence of existing uses on the resource, and ground water supply. The specific approaches used by

FIGURE 5.4 General areas of ground water significance in Florida. (Map provided by Florida Department of Environmental Regulation, Bureau of Drinking Water and Ground Water Resources.)

the WMDs varied, however. For example, the St. Johns River WMD used a GIS-based map overlay and DRASTIC-like numerical index approach that rated the following attributes: recharge, transmissivity, water quality, thickness of potable water, potential water expansion areas, and spring flow capture zones. The Southwest Florida WMD also used a map overlay and index approach which considered four criteria, and GIS tools for mapping. Existing databases were considered inadequate to generate a DRASTIC map for the Suwannee River WMD, but the map produced using an overlay approach was considered to be similar to DRASTIC maps in providing a general depiction of aquifer vulnerability.

In the November 1988, Florida voters approved an amendment to the Florida Constitution allowing land producing high recharge to Florida's aquifers to be classified and assessed for ad valorem tax purposes based on character or use. Such recharge areas are expected to be located primarily in the upland, sandy ridge areas. The Bluebelt Commission appointed by the 1989 Florida Legislature, studied the complex issues involved and recommended that the tax incentive be offered to owners of such high recharge areas if their land is left undeveloped (SFWMD 1991). The land eligible

for classification as "high water recharge land" must meet the following criteria established by the commission:

The parcel must be located in the high recharge areas designated on maps supplied by each of the five WMDs.

The high recharge area of the parcel must be at least 10 acres.

The land use must be vacant or single-family residential.

The parcel must not be receiving any other special assessment, such as Greenbelt classification for agricultural lands.

Two bills related to the implementation of the Bluebelt program are being considered by the 1993 Florida legislation.

THE SAN JOAQUIN VALLEY

Pesticide contamination of ground water resources is a serious concern in California's San Joaquin Valley (SJV). Contamination of the area's aquifer system has resulted from a combination of natural geologic conditions and human intervention in exploiting the SJV's natural resources. The SJV is now the principal target of extensive ground water monitoring activities in the state.

Agriculture has imposed major environmental stresses on the SJV. Natural wetlands have been drained and the land reclaimed for agricultural purposes. Canal systems convey water from the northern, wetter parts of the state to the south, where it is used for irrigation and reclamation projects. Tens of thousands of wells tap the sole source aquifer system to supply water for domestic consumption and crop irrigation. Cities and towns have sprouted throughout the region and supply the human resources necessary to support the agriculture and petroleum industries.

Agriculture is the principal industry in California. With 1989 cash receipts of more than $17.6 billion, the state's agricultural industry produced more than 50 percent of the nation's fruits, nuts, and vegetables on 3 percent of the nation's farmland. California agriculture is a diversified industry that produces more than 250 crop and livestock commodities, most of which can be found in the SJV.

Fresno County, the largest agricultural county in the state, is situated in the heart of the SJV, between the San Joaquin River to the north and the Kings River on the south. Grapes, stone fruits, and citrus are important commodities in the region. These and many other commodities important to the region are susceptible to nematodes which thrive in the county's coarse-textured soils.

While agricultural diversity is a sound economic practice, it stimulates the growth of a broad range of pest complexes, which in turn dictates greater reliance on agricultural chemicals to minimize crop losses to pests, and maintain productivity and profit. Domestic and foreign markets demand high-quality and cosmetically appealing produce, which require pesticide use strategies that rely on pest exclusion and eradication rather than pest management.

Hydrogeologic Setting

The San Joaquin Valley (SJV) is at the southern end of California's Central Valley. With its northern boundary just south of Sacramento, the Valley extends in a southeasterly direction about 400 kilometers (250 miles) into Kern County. The SJV averages 100 kilometers (60 miles) in width and drains the area between the Sierra Nevada on the east and the California Coastal Range on the west. The rain shadow caused by the Coastal Range results in the predominantly xeric habitat covering the greater part of the valley floor where the annual rainfall is about 25 centimeters (10 inches). The San Joaquin River is the principal waterway that drains the SJV northward into the Sacramento Delta region.

The soils of the SJV vary significantly. On the west side of the valley, soils are composed largely of sedimentary materials derived from the Coastal Range; they are generally fine-textured and slow to drain. The arable soils of the east side developed on relatively unweathered, granitic sediments. Many of these soils are wind-deposited sands underlain by deep coarse-textured alluvial materials.

From the mid-1950s until 1977, dibromochloropropane (DBCP) was the primary chemical used to control nematodes. DBCP has desirable characteristics for a nematocide. It is less volatile than many other soil fumigants, such as methylbromide; remains active in the soil for a long time, and is effective in killing nematodes. However, it also causes sterility in human males, is relatively mobile in soil, and is persistent. Because of the health risks associated with consumption of DBCP treated foods, the nematocide was banned from use in the United States in 1979. After the ban, several well water studies were conducted in the SJV by state, county and local authorities. Thirteen years after DBCP was banned, contamination of well waters by the chemical persists as a problem in Fresno County.

Public concern over pesticides in ground water resulted in passage of the California Pesticide Contamination Prevention Act (PCPA) of 1985. It is a broad law that establishes the California Department of Pesticide Regulation

as the lead agency in dealing with issues of ground water contamination by pesticides. The PCPA specifically requires:

pesticide registrants to collect and submit specific chemical and environmental fate data (e.g., water solubility, vapor pressure, octanol-water partition coefficient, soil sorption coefficient, degradation half-lives for aerobic and anaerobic metabolism, Henry's Law constant, hydrolysis rate constant) as part of the terms for registration and continued use of their products in California.

establishment of numerical criteria or standards for physical-chemical characteristics and environmental fate data to determine whether a pesticide can be registered in the state that are at least as stringent as those standards set by the EPA,

soil and water monitoring investigations be conducted on:

pesticides with properties that are in violation of the physical-chemical standards set in 2 above, and

pesticides, toxic degradation products or other ingredients that are:

contaminants of the state's ground waters, or

found at the deepest of the following soil depths:

2.7 meters (8 feet) below the soil surface,

below the crop root zone, or

below the microbial zone, and

creation of a database of wells sampled for pesticides with a provision requiring all agencies to submit data to the California Department of Pesticide Regulation (CDPR).

Difficulties associated with identifying the maximum depths of root zone and microbial zone have led to the establishment of 8 feet as a somewhat arbitrary but enforceable criterion for pesticide leaching in soils.

Selection and Implementation of an Approach

Assessment of ground water vulnerability to pesticides in California is a mechanical rather than a scientific process. Its primary goal is compliance with the mandates established in the PCPA. One of these mandates requires that monitoring studies be conducted in areas of the state where the contaminant pesticide is used, in other areas exhibiting high risk portraits (e.g., low organic carbon, slow soil hydrolysis, metabolism, or dissipation), and in areas where pesticide use practices present a risk to the state's ground water resources.

The numerical value for assessments was predetermined by the Pesticide Use Report (PUR) system employed in the state. Since the early

1970s, California has required pesticide applicators to give local authorities information on the use of restricted pesticides. This requirement was extended to all pesticides beginning in 1990. Application information reported includes names of the pesticide(s) and commodities, the amount applied, the formulation used, and the location of the commodity to the nearest section (approximately 1 square mile) as defined by the U.S. Rectangular Coordinate System. In contrast to most other states that rely on county pesticide sales in estimating pesticide use, California can track pesticide use based on quantities applied to each section. Thus, the section, already established as a political management unit, became the basic assessment unit.

The primary criteria that subject a pesticide to investigation as a ground water pollutant are:

detection of the pesticide or its metabolites in well samples, or

its failure to conform to the physical-chemical standards set in accordance with the PCPA, hence securing its position on the PCPA's Ground Water Protection List of pesticides having a potential to pollute ground water.

In either case, relatively large areas surrounding the original detection site or, in the latter case, high use regions are monitored via well surveys. Positive findings automatically increase the scope of the surveys, and since no tolerance levels are specified in the PCPA, any detectable and confirmed result establishes a pesticide as a contaminant.

When a pesticide or its degradation products is detected in a well water sample and the pesticide is judged to have contaminated the water source as a result of a legal agricultural use, the section the well is in is declared a Pesticide Management Zone (PMZ). Further application of the detected pesticide within PMZ boundaries may be prohibited or restricted, depending on the degree of contamination and subject to the availability of tried and tested modifications in management practices addressing environmental safety in use of the pesticide. PMZs are pesticide-specific—each contaminant pesticide has its own set of PMZs which may or may not overlap PMZs assigned another pesticide. Currently, consideration is being given to the extension of PMZs established for one chemical to other potential pesticide pollutants. In addition to monitoring activities in PMZs, protocols have been written to monitor ground water in sections adjacent to a PMZ. Monitoring of adjacent sections has resulted in many new PMZs. Currently, California has 182 PMZs involving five registered pesticides.

California has pursued this mechanical approach to assessing ground water vulnerability to pesticides for reasons that cover a spectrum of political, economic, and practical concerns. As noted earlier, the scale of the assessment unit was set at the section level because it is a well-defined

geopolitical unit used in the PUR system. Section boundaries frequently are marked by roads and highways, which allows the section to be located readily and makes enforcement of laws and regulations more practical. California law also requires that well logs be recorded by drillers for all wells in the state. Well-site information conforms to the U.S. Rectangular Coordinate System's township, range, and section system.

The suitability and reliability of databases available for producing vulnerability assessments was a great concern before passage of the PCPA in 1985. Soil survey information holds distinct advantages for producing assessments and developing best management practices strategies, but it was not available in a format that could work in harmony with PUR sections. To date, several areas of the SJV are not covered by a modern soil survey; they include the western part of Tulare County, which contains 34 PMZs. Other vadose zone data were sparse, it available at all.

The use of models was not considered appropriate, given the available data and because no single model could cope with the circumstances in which contaminated ground water sources were being discovered in the state. While most cases of well contamination were associated with the coarse-textured soils of the SJV and the Los Angeles Basin, several cases were noted in areas of the Central Valley north of the SJV, where very dense fine-textured soils (vertisols and other cracking clays) were dominant.

The potential vagaries and uncertainties associated with more scientific approaches to vulnerability assessment, given the tools available when the PCPA was enacted, presented too large a risk for managers to consider endorsing their use. In contrast, the basic definition of the PMZ is difficult to challenge (pesticide contamination has been detected or not detected) in the legal sense. And the logic of investing economic resources in areas immediately surrounding areas of acknowledged contamination are relatively undisputable. The eastern part of the SJV contains more than 50 percent of the PMZs in the state. Coarse-textured soils of low carbon content are ubiquitous in this area and are represented in more than 3,000 sections. The obvious contamination scenario is the normal scenario in the eastern SJV, and because of its size it creates a huge management problem. While more sophisticated methods for assessing ground water vulnerability have been developed, a question that begs to be asked is "How would conversion to the use of enhanced techniques for evaluating ground water vulnerability improve ground water protection policy and management in the SJV?"

More than 90 percent of the population of Hawaii depends on ground water (nearly 200 billion gallons per day) for their domestic supply (Au 1991). Ground water contamination is of special concern in Hawaii, as in other insular systems, where alternative fresh water resources are not readily available or economically practical. Salt water encroachment, caused by pumping, is by far the biggest source of ground water contamination in Hawaii; however, nonpoint source contamination from agricultural chemicals is increasingly a major concern. On Oahu, where approximately 80 percent of Hawaii's million-plus population resides, renewable ground water resources are almost totally exploited; therefore, management action to prevent contamination is essential.

Each of the major islands in the Hawaiian chain is formed from one or more shield volcanoes composed primarily of extremely permeable thin basaltic lava flows. On most of the Hawaiian islands the margins of the volcanic mountains are overlapped by coastal plain sediments of alluvial and marine origin that were deposited during periods of volcanic quiescence. In general, the occurrence of ground water in Hawaii, shown in Figure 5.5 , falls into three categories: (1) basal water bodies floating on and displacing salt water, (2) high-level water bodies impounded within compartments formed by impermeable dikes that intrude the lava flows, and (3) high-level water bodies perched on ash beds or soils interbedded with

FIGURE 5.5 Cross section of a typical volcanic dome showing the occurrence of ground water in Hawaii (After Peterson 1972. Reprinted, by permission, from Water Well Journal Publishing Company, 1972.)

thin lava flows on unconformities or on other relatively impervious lava flows (Peterson 1972).

A foundation of the tourist industry in Hawaii is the pristine environment. The excellent quality of Hawaii's water is well known. The public has demanded, and regulatory agencies have adopted, a very conservative, zero-tolerance policy on ground water contamination. The reality, however, is that past, present, and future agricultural, industrial, and military activities present potentially significant ground water contamination problems in Hawaii.

Since 1977 when 1,874 liters of ethylene dibromide (EDB) where spilled within 18 meters of a well near Kunia on the island of Oahu, the occurrence and distribution of contaminants in Hawaii's ground water has been carefully documented by Oki and Giambelluca (1985, 1987) and Lau and Mink (1987). Before 1981, when the nematocide dibromochloropropane (DBCP) was found in wells in central Oahu, the detection limit for most chemicals was too high to reveal the low level of contamination that probably had existed for many years.

Concern about the fate of agriculture chemicals led the Hawaii State Department of Agriculture to initiate a large sampling program to characterize the sources of nonpoint ground water contamination. In July 1983, 10 wells in central Oahu were closed because of DBCP and EDB contamination. The public has been kept well informed of possible problems through the publication of maps of chemicals detected in ground water in the local newspaper. Updated versions of these maps are shown in Figures 5.6a , b , c , and d .

In Hawaii, interagency committees, with representation from the Departments of Health and Agriculture, have been formed to address the complex technical and social questions associated with ground water contamination from agricultural chemicals. The Hawaii legislature has provided substantial funding to groups at the University of Hawaii to develop the first GIS-based regional scale chemical leaching assessment approach to aid in pesticide regulation. This effort, described below, has worked to identify geographic areas of concern, but the role the vulnerability maps generated by this system will play in the overall regulatory process is still unclear.

Agrichemicals are essential to agriculture in Hawaii. It is not possible to maintain a large pineapple monoculture in Hawaii without nematode control using pesticides. Pineapple and sugar growers in Hawaii have generally employed well controlled management practices in their use of fertilizers, herbicides, and insecticides. In the early 1950s, it was thought that organic chemicals such as DBCP and EDB would not leach to ground water

FIGURE 5.6a The occurrence and distribution of ground water contamination on the Island of Oahu. (Map provided by Hawaii State Department of Health.)

FIGURE 5.6b The occurrence and distribution of ground water contamination on the Island of Hawaii. (Map provided by Hawaii State Department of Health.)

FIGURE 5.6c The occurrence and distribution of ground water contamination on the Island of Maui. (Map provided by Hawaii State Department of Health.)

FIGURE 5.6d The occurrence and distribution of ground water contamination on the Island of Kauai. (Map provided by Hawaii State Department of Health.)

because (1) the chemicals are highly sorbed in soils with high organic carbon contents, (2) the chemicals are highly volatile, and (3) the water table is several hundred meters below the surface. Measured concentrations of DBCP and EDB down to 30 meters at several locations have shown the original assessment to be wrong. They have resulted in an urgent need to understand processes such as preferential flow better and to predict if the replacement chemicals used today, such as Telon II, will also leach to significant depths.

Leaching of pesticides to ground water in Hawaii could take decades. This time lag could lead to a temporary false sense of security, as happened in the past and potentially result in staggering costs for remedial action. For this reason, mathematical models that permit the user to ask ''what if" questions have been developed to help understand what the future may hold under certain management options. One needs to know what the fate of chemicals applied in the past will be and how to regulate the chemicals considered for use in the future; models are now being developed and used to help make these vulnerability assessments.

Researchers have embarked on several parallel approaches to quantitatively assess the vulnerability of Hawaii's ground water resources, including: (1) sampling, (2) physically-based numerical modeling, and (3) vulnerability mapping based on a simple chemical leaching index. Taken together these approaches have provided insight and guidance for work on a complex, spatially and temporally variable problem.

The sampling programs (Wong 1983 and 1987, Peterson et al. 1985) have shown that the chemicals applied in the past do, in fact, leach below the root zone, contrary to the original predictions, and can eventually reach the ground water. Experiments designed to characterize the nuances of various processes, such as volatilization, sorption, and degradation, have been conducted recently and will improve the conceptualization of mathematical models in the future.

The EPA's Pesticide Root Zone Model (PRZM), a deterministic-empirical/conceptual fluid flow/solute transport model, has been tested by Loague and co-workers (Loague et al. 1989a, b; Loague 1992) against measured concentration profiles for DBCP and EDB in central Oahu. These simulations illustrate that the chemicals used in the past can indeed move to considerable depths. Models of this kind, once properly validated, can be used to simulate the predicted fate of future pesticide applications. One must always remember, however, that numerical simulations must be interpreted in terms of the limiting assumptions associated with model and data errors.

Ground water vulnerability maps and assessments of their uncertainty were pioneered at the University of Hawaii in the Department of Agriculture Engineering (Khan and Liang 1989, Loague and Green 1990a). These pesticide leaching assessments were made by coupling a simple mobility index to a geographic information system. Loague and coworkers have investigated the uncertainty in these maps owing to data and model errors (Loague and Green 1988; Loague et al. 1989c, 1990; Loague and Green 1990b, 1990c; Loague 1991; Kleveno et al. 1992; Yost et al. 1993). The Hawaiian database on soils, climate, and chemicals is neither perfect nor poor for modeling applications; it is typical of what exists in most states—major extrapolations are required to estimate the input parameters required for almost any chemical fate model.

Sampling from wells in Hawaii has shown the concentrations of various chemicals, both from agriculture and industrial sources, which have leached to ground water in Hawaii. These concentrations, in general, are low compared to the levels detected in other states and for the most part are below health advisory levels established by EPA. In some instances contamination has not resulted from agriculture, but rather from point sources such as chemical loading and mixing areas and possibly from ruptured fuel lines. The widespread presence of trichloropropane (TCP) in Hawaii's ground water and deep soil cores at concentrations higher than DBCP was totally unexpected. TCP was never applied as a pesticide, but results from the manufacture of the fumigant DD, which was used until 1977 in pineapple culture. The occurrence of TCP illustrates that one must be aware of the chemicals applied as well as their components and transformation products.

Wells have been closed in Hawaii even though the measured contaminant concentrations have been below those considered to pose a significant health risk. At municipal well locations in central Oahu, where DBCP, EDB, and/or TCP have been detected, the water is now passed through carbon filters before it is put into the distribution system. The cost of this treatment is passed on to the water users, rather than to those who applied the chemicals.

The pesticide leaching assessment maps developed by Khan and Liang (1989) are intended for incorporation into the regulatory process. Decisions are not made on the basis of the red and green shaded areas for different chemicals (see Plate 3 ), but this information is considered. The uncertainty analysis by Loague and coworkers has shown some of the limitations of deterministic assessments in the form of vulnerability maps and provided initial guidance on data shortfalls.

APPLICATION OF A VULNERABILITY INDEX FOR DECISION-MAKING AT THE NATIONAL LEVEL

Need for a vulnerability index.

A vulnerability index for ground water contamination by pesticides has been developed and used by USDA as a decision aid to help attain the objectives of the President's Water Quality Initiative (see Box 1.1 ). A vulnerability index was needed for use in program management and to provide insight for policy development. Motivation for the development of the vulnerability index was provided by two specific questions:

Given limited resources and the geographic diversity of the water quality problems associated with agricultural production, what areas of the country have the highest priority for study and program implementation?

What policy implications emerge from the spatial patterns of the potential for conamination from a national perspective, given information currently available about farming practices and chemical use in agriculture?

Description of the Vulnerability Index

A vulnerability index was derived to evaluate the likelihood of shallow ground water contamination by pesticides used in agriculture in one area compared to another area. Because of the orientation of Initiative policies to farm management practices, it was necessary that the vulnerability measure incorporate field level information on climate, soils, and chemical use. It also needed to be general enough to include all areas of the country and all types of crops grown.

A Ground Water Vulnerability Index for Pesticides (GWVIP) was developed by applying the Soil-Pesticide Interaction Screening Procedure (SPISP) developed by the Soil Conservation Service to the National Resource Inventory (NRI) land use database for 1982 and the state level pesticide use database created by Resources for the Future (Gianessi and Puffer 1991). Details of the computational scheme and databases used are described by Kellogg et al. (1992). The 1982 NRI and the associated SOIL-5 database provide information on soil properties and land use at about 800,000 sample points throughout the continental United States. This information is sufficient to apply the SPISP to each point and thus obtain a relative measure of the soil leaching potential throughout the country. The RFF pesticide use database was used to infer chemical use at each point on the basis of the crop type recorded in the NRI database. By taking advantage of the statistical properties of the NRI database, which is based on a statistical survey

sampling design, the GWVIP score at each of the sample points can be statistically aggregated for making comparisons among regions.

Since the GWVIP is an extension of a screening procedure, it is designed to minimize the likelihood of incorrectly identifying an area as having a low potential for contamination—that is, false negatives are minimized and false positives are tolerated. The GWVIP is designed to classify an area as having a potential problem even if the likelihood is small.

GWVIP scores were graphically displayed after embedding them in a national cartographic database consisting of 13,172 polygons created by overlaying the boundaries of 3,041 counties, 189 Major Land Resource Areas (MLRAs), 2,111 hydrologic units, and federal lands.

Three caveats are especially important in using the GWVIP and its aggregates as a decision aid:

Land use data are for 1982 and do not represent current cropping patterns in some parts of the country. Although total cropland acreage has remained fairly stable over the past 10 years, there has been a pronounced shift from harvested cropland to cropland idled in government programs.

The approach uses a simulation model that predicts the amount of chemical that leaches past the root zone. In areas where the water table is near the surface, these predictions relate directly to shallow ground water contamination. In other areas a time lag is involved. No adjustment was made for areas with deep water tables.

No adjustment in chemical use is made to account for farm management factors, such as chemical application rates and crop rotations. The approach assumes that chemical use is the same for a crop grown as part of a rotation cropping system as for continuous cropping. Since the chemical use variable in the GWVIP calculation is based on acres of land treated with pesticides, application rates are also not factored into the analysis.

Application to Program Management

By identifying areas of the country that have the highest potential for leaching of agrichemicals, the GWVIP can serve as a basis for selecting sites for implementation of government programs and for more in-depth research on the environmental impact of agrichemical use. These sites cannot be selected exclusively on the basis of the GWVIP score, however, because other factors, such as surface water impacts and economic and demographic factors, are also important.

For example, the GWVIP has been used as a decision aid in selecting sites for USDA's Area Study Program, which is designed to provide chemical use and farming practice information to aid in understanding the relationships among farming activities, soil properties, and ground water quality.

The National Agricultural Statistics Service interviews farm operators in 12 major watersheds where the U.S. Geological Survey is working to measure the quality of surface and ground water resources under its National Water Quality Assessment Program. At the conclusion of the project, survey information will be combined with what is learned in other elements of the President's Water Quality Initiative to assess the magnitude of the agriculture-related water quality problem for the nation as a whole and used to evaluate the potential economic and environmental effects of Initiative policies of education, technical assistance, and financial assistance if implemented nationwide.

To meet these objectives, each Area Study site must have a high potential for ground water contamination relative to other areas of the country. A map showing the average GWVIP for each of the 13,172 polygons comprising the continental United States, shown in Plate 3 , was used to help select the sites. As this map shows, areas more likely to have leaching problems with agrichemicals than other areas of the country occur principally along the coastal plains stretching from Alabama and Georgia north to the Chesapeake Bay area, the corn belt states, the Mississippi River Valley, and the irrigated areas in the West. Sites selected for study in 1991 and 1992 include four from the eastern coastal plain (Delmarva Peninsula, southeastern Pennsylvania, Virginia and North Carolina, and southern Georgia), four from the corn belt states (Nebraska, Iowa, Illinois, and Indiana), and two from the irrigated areas in the West (eastern Washington and southeastern Idaho). Four additional sites will be selected for study in 1993.

Application to Policy Analysis and Development

The GWVIP has also been used by USDA to provide a national perspective on agricultural use of pesticides and the potential for ground water contamination to aid in policy analysis and development.

The geographic distribution of GWVIP scores has shown that the potential for ground water contamination is diverse both nationally and regionally. Factors that determine intrinsic vulnerability differ in virtually every major agricultural region of the country. Whether an impact is realized in these intrinsically vulnerable areas depends on the activities of producers—such as the type of crop planted, chemical use, and irrigation practices—which also vary both nationally and regionally. High vulnerability areas are those where a confluence of these factors is present. But not all cropland is vulnerable to leaching. About one-fourth of all cropland has GWVIP scores that indicate very low potential for ground water contamination from the use of agrichemicals. Nearly all agricultural states have significant acreage that meets this low vulnerability criterion. Areas of the country identified as being in a high vulnerability group relative to potential

for agrichemical leaching also have significant acreages that appear to have low vulnerability.

This mix of relative vulnerabilities both nationally and regionally has important policy implications. With the potential problem so diverse, it is not likely that simple, across-the-board solutions will work. Simple policies—such as selective banning of chemicals—may reduce the potential for ground water contamination in problem areas while imposing unnecessary costs on farming in nonproblem areas. The geographic diversity of the GWVIP suggests that the best solutions will come from involvement of both local governments and scientists with their state and national counter-parts to derive policies that are tailored to the unique features of each problem area.

In the future, USDA plans to use vulnerability indexes, like the GWVIP, in conjunction with economic models to evaluate the potential for solving agriculture-related water quality problems with a nationwide program to provide farmers with the knowledge and technical means to respond voluntarily to water quality concerns.

These six case studies illustrate how different approaches to vulnerability assessment have evolved under diverse sets of management requirements, data constraints, and other technical considerations. In addition, each of these examples shows that vulnerability assessment is an ongoing process through which information about a region's ground water resources and its quality can be organized and examined methodically.

In Iowa, the Iowa DNR staff elected to keep their vulnerability characterization efforts as simple as possible, and to use only properties for which data already existed or could be easily checked. They assumed that surficial features such as the soil are too thin and too disrupted by human activities (e.g., tillage, abandoned wells) to provide effective ground water protection at any particular location and sought to identify a surrogate measure for average travel time from the land surface to the aquifer. Thus, a ground water vulnerability map was produced which represents vulnerability primarily on the basis of depth to ground water and extent of overlying materials. Wells and sinkholes are also shown. The results are to be used for informing resource managers and the public of the vulnerability of the resource and to determine the type of information most needed to develop an even better understanding of the vulnerability of Iowa's ground water.

The Cape Cod approach to ground water vulnerability assessment is perhaps one of the oldest and most sophisticated in the United States. Driven by the need to protect the sole source drinking water aquifer underlying this sandy peninsula, the vulnerability assessment effort has focused on the identification

and delineation of the primary recharge areas for the major aquifers. This effort began with a simple mass balance approach which assumed even recharge within a circular area around each drinking water well. It has since evolved to the development of a complex, particle-tracking three-dimensional model that uses site-specific data to delineate zones of contribution. Bolstered by strong public concern, Cape Cod has been able to pursue an ambitious and sophisticated agenda for resource protection, and now boasts a sophisticated differential management ground water protection program.

In Florida, ground water resource managers rely on a combination of monitoring and vulnerability assessment techniques to identify high recharge areas the develop the state ground water protection program. Overlay and index methods, including several modified DRASTIC maps were produced to identify areas of ground water significance in support of decision making in state land acquisition programs aimed at ground water protection. In addition, several monitoring networks have been established to assess background water quality and monitor actual effects in areas identified as highly vulnerable. The coupling of ground water vulnerability assessments with monitoring and research efforts, provides the basis of an incremental and evolving ground water protection program in Florida.

The programs to protect ground water in California's intensely agricultural San Joaquin Valley are driven largely by compliance with the state Pesticide Contamination Prevention Act. The California Department of Pesticide Regulation determined that no model would be sufficient to cover their specific regulatory needs and that the available data bases were neither suitable nor reliable for regulatory purposes. Thus, a ground water protection program was built on the extensive existing pesticide use reporting system and the significant ground water monitoring requirements of the act. Using farm sections as management units, the state declares any section in which a pesticide or its degradation product is detected as a pesticide management zone and establishes further restrictions and monitoring requirements. Thus, the need to devise a defensible regulatory approach led California to pursue a mechanistic monitoring based approach rather than a modeling approach that would have inherent and difficult to quantify uncertainties.

In contrast, the approach taken in Hawaii involves an extensive effort to understand the uncertainty associated with the assessment models used. The purpose of this is to provide guidance to, but not the sole basis for, the pesticide regulation program. The combined use of sampling, physically-based numerical modeling, and a chemical leaching index has led to extensive improvements in the understanding of the fate of pesticides in the subsurface environment. Uncertainty analyses are used to determine where additional information would be most useful.

Finally, USDA's Ground Water Vulnerability Index for Pesticides illustrates a national scale vulnerability assessment developed for use as a decision aid and analytical tool for national policies regarding farm management and water quality. This approach combines nationally available statistical information on pesticide usage and soil properties with a simulation model to predict the relative likelihood of contamination in cropland areas. USDA has used this approach to target sites for its Area Study Program which is designed to provide information to farmers about the relationships between farm management practices and water quality. The results of the GWVIP have also indicated that, even at the regional level, there is often an mix of high and low vulnerability areas. This result suggests that effective ground water policies should be tailored to local conditions.

Au, L.K.L. 1991. The Relative Safety of Hawaii's Drinking Water. Hawaii Medical Journal 50(3): 71-80.

Barlow, P.M. 1993. Particle-Tracking Analysis of Contributing Areas of Public-Supply Wells in Simple and Complex Flow Systems, Cape Cod, Massachusetts. USGS Open File Report 93-159. Marlborough, Massachusetts: U.S. Geological Survey.

Britt, J.K., S.E. Dwinell, and T.C. McDowell. 1992. Matrix decision procedure to assess new pesticides based on relative ground water leaching potential and chronic toxicity. Environ. Toxicol. Chem. 11: 721-728.

Cape Cod Commission (CCC). 1991. Regional Policy Plan. Barnstable, Massachusetts: Cape Cod Commission.

Cape Cod Planning and Economic Development Commission (CCPEDC). March 1978a. Draft Area Wide Water Quality Management Plan for Cape Cod. Barnstable, Massachusetts: Cape Cod Commission.

Cape Cod Planning and Economic Development Commission (CCPEDC). September 1978b. Final Area Wide Water Quality Management Plan for Cape Cod. Barnstable, Massachusetts: Cape Cod Commission.

Department of Environmental Protection, Division of Water Supply (DEP-WS). 1991. Guidelines and Policies for Public Water Supply Systems. Massachusetts Department of Environmental Protection.

Gianessi, L.P., and C.A. Puffer. 1991. Herbicide Use in the United States: National Summary Report. Washington, D.C.: Resources for the Future.

Guswa, J.H., and D.R. LeBlanc. 1981. Digital Models of Ground water Flow in the Cape Cod Aquifer System, MA. USGS Water Supply Paper 2209. U.S. Geological Survey.

Heath, D.L. 1988. DRASTIC mapping of aquifer vulnerability in eastern Barnstable and western Yarmouth, Cape Cod, Massachusetts. In Appendix D, Cape Cod Aquifer Management Project, Final Report, G.A. Zoto and T. Gallagher, eds. Boston: Massachusetts Department of Environmental Quality Engineering.

Horsely, S.W. 1983. Delineating zones of contribution of public supply wells to protect ground water . In Proceedings of the National Water Well Association Eastern Regional Conference, Ground-Water Management, Orlando, Florida.

Hoyer, B.E. 1991. Ground water vulnerability map of Iowa. Pp. 13-15 in Iowa Geology, no. 16. Iowa City, Iowa: Iowa Department of Natural Resources.

Hoyer, B.E., J.E. Combs, R.D. Kelley, C. Cousins-Leatherman, and J.H. Seyb. 1987. Iowa Ground water Protection Strategy. Des Moines: Iowa Department of Natural Resources.

Kellogg, R.L., M.S. Maizel, and D.W. Goss. 1992. Agricultural Chemical Use and Ground Water Quality: Where Are the Potential Problems? Washington, D.C.: U.S. Department of Agriculture, Soil Conservation Service.

Khan, M.A., and T. Liang. 1989. Mapping pesticide contamination potential. Environmental Management 13(2):233-242.

Kleveno, J.J., K. Loague, and R.E. Green. 1992. An evaluation of a pesticide mobility index: Impact of recharge variation and soil profile heterogeneity. Journal of Contaminant Hydrology 11(1-2):83-99.

Land Acquisition Advisory Council (LAAC). 1991. Ground Water Resources Committee Final Report: Florida Preservation 2000 Needs Assessment. Tallahassee, Florida: Department of Environmental Regulation. 39 pp.

Lau, L.S., and J.F. Mink. 1987. Organic contamination of ground water: A learning experience. J. American Water Well Association 79(8):37-42.

LeBlanc, D.R., and J.H. Guswa. 1977. Water-Table Map of Cape Cod, MA. May 23-27, 1976, USGS Open File Report 77-419, scale 1:48,000.

Loague, K. 1991. The impact of land use on estimates of pesticide leaching potential: Assessments and uncertainties. Journal of Contaminant Hydrology 8: 157-175.

Loague, K. 1992. Simulation of organic chemical movement in Hawaii soils with PRZM: 3. Calibration. Pacific Science 46(3):353-373.

Loague, K.M., and R.E. Green. 1988. Impact of data-related uncertainties in a pesticide leaching assessment. Pp. 98-119 in Methods for Ground Water Quality Studies, D.W. Nelson and R.H. Dowdy, eds. Lincoln, Nebraska: Agricultural Research Division, University of Nebraska.

Loague, K., and R.E. Green. 1990a. Comments on "Mapping pesticide contamination potential," by M.A. Khan and T. Liang. Environmental Management 4:149-150.

Loague, K., and R.E. Green. 1990b. Uncertainty in Areal Estimates of Pesticide Leaching Potential. Pp. 62-67 in Transactions of 14th International Congress of Soil Science. Kyoto, Japan: International Soil Science Society.

Loague, K., and R.E. Green. 1990c. Criteria for evaluating pesticide leaching models. Pp. 175-207 in Field-Scale Water and Solute Flux in Soils, K. Roth, H. Flühler, W.A. Jury, and J.C. Parker, eds. Basel, Switzerland: Birkhauser Verlag.

Loague, K.M., R.E. Green, C.C.K. Liu, and T.C. Liang. 1989a. Simulation of organic chemical movement in Hawaii soils with PRZM: 1. Preliminary results for ethylene dibromide. Pacific Science 43(1):67-95.

Loague, K., T.W. Giambelluca, R.E. Green, C.C.K. Liu, T.C. Liang, and D.S. Oki. 1989b. Simulation of organic chemical movement in Hawaii soils with PRZM: 2. Predicting deep penetration of DBCP, EDB, and TCP. Pacific Science 43(4):362-383.

Loague, K.M., R.S. Yost, R.E. Green, and T.C. Liang. 1989c. Uncertainty in a pesticide leaching assessment for Hawaii. Journal of Contaminant Hydrology 4:139-161.

Loague, K., R.E. Green, T.W. Giambelluca, T.C. Liang, and R.S. Yost. 1990. Impact of uncertainty in soil, climatic, and chemical information in a pesticide leaching assessment. Journal of Contaminant Hydrology 5:171-194.

Maddox, G., and J. Spicola. 1991. Ground Water Quality Monitoring Network. Tallahassee, Florida: Florida Department of Environmental Regulation. 20 pp.

Maddox, G., J. Lloyd, T. Scott, S. Upchurch, and R. Copeland, eds. 1993. Florida's Ground Water Quality monitoring Program: Background Hydrogeochemistry. Florida Geological Survey Special Publication #34. Tallahassee, Florida: Florida Department of Environmental Regulation in cooperation with Florida Geological Survey.

National Research Council (NRC). 1986. Ground Water Quality Protection: State and Local Strategies. Washington, D.C.: National Academy Press.

Oki, D.S., and T.W. Giambelluca. 1985. Subsurface Water and Soil Quality Data Base for State of Hawaii: Part 1. Spec. Rept. 7. Manoa, Hawaii: Water Resources Research Center, University of Hawaii at Manoa.

Oki, D.S., and T.W. Giambelluca. 1987. DBCP, EDB, and TCP contamination of ground water in Hawaii. Ground Water 25:693-702.

Olimpio, J.C., E.C. Flynn, S. Tso, and P.A. Steeves. 1991. Use of a Geographic Information System to Assess Risk to Ground-Water Quality at Public-Supply Wells, Cape Cod, Massachusetts. Boston, Massachusetts: U.S. Geological Survey.

Peterson, F.L. 1972. Water development on tropic volcanic islands—Type example: Hawaii. Ground Water 5:18-23.

Peterson, F.L., K.R. Green, R.E. Green, and J.N. Ogata. 1985. Drilling program and pesticide analysis of core samples from pineapple fields in central Oahu. Water Resources Research Center, University of Hawaii at Manoa, Special Report 7.5. Photocopy.

Southwest Florida Water Management Districts (SFWMD). 1991. The Bluebelt Commission. Brooksville, Florida: Southwest Florida Water Management Districts.

U.S. Bureau of the Census. 1991. Statistical Abstracts of the United States: 1991, 111th edition. Washington, D.C.: U.S. Government Printing Office.

Wong, L. 1983. Preliminary report on soil sampling EDB on Oahu. Pesticide Branch, Div. of Plant Industry, Department of Agriculture, State of Hawaii. Photocopy.

Wong, L. 1987. Analysis of ethylene dibromide distribution in the soil profile following shank injection for nematode control in pineapple culture. Pp. 28-40 in Toxic Organic Chemicals in Hawaii's Water Resources, P.S.C. Rao and R.E. Green, eds. Ser. 086. Honolulu: Hawaii Inst. Trop Agric. Hum. Resources Res. Exten. University of Hawaii.

Yost, R.S., K. Loague, and R.E. Green. 1993. Reducing variance in soil organic carbon estimates—soil classification and geostatistical approaches. Geoderma 57(3):247-262

Since the need to protect ground water from pollution was recognized, researchers have made progress in understanding the vulnerability of ground water to contamination. Yet, there are substantial uncertainties in the vulnerability assessment methods now available.

With a wealth of detailed information and practical advice, this volume will help decision-makers derive the most benefit from available assessment techniques. It offers:

• Three laws of ground water vulnerability.
• Six case studies of vulnerability assessment.
• Guidance for selecting vulnerability assessments and using the results.
• Reviews of the strengths and limitations of assessment methods.
• Information on available data bases, primarily at the federal level.

This book will be indispensable to policymakers and resource managers, environmental professionals, researchers, faculty, and students involved in ground water issues, as well as investigators developing new assessment methods.

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Discharge from a Chinese fertilizer factory winds its way toward the Yellow River. Like many of the world's rivers, pollution remains an ongoing problem.

Water pollution is a rising global crisis. Here’s what you need to know.

The world's freshwater sources receive contaminants from a wide range of sectors, threatening human and wildlife health.

From big pieces of garbage to invisible chemicals, a wide range of pollutants ends up in our planet's lakes, rivers, streams, groundwater, and eventually the oceans. Water pollution—along with drought, inefficiency, and an exploding population—has contributed to a freshwater crisis , threatening the sources we rely on for drinking water and other critical needs.

Research has revealed that one pollutant in particular is more common in our tap water than anyone had previously thought: PFAS, short for poly and perfluoroalkyl substances. PFAS is used to make everyday items resistant to moisture, heat, and stains; some of these chemicals have such long half-lives that they are known as "the forever chemical."

Safeguarding water supplies is important because even though nearly 70 percent of the world is covered by water, only 2.5 percent of it is fresh. And just one percent of freshwater is easily accessible, with much of it trapped in remote glaciers and snowfields.

Water pollution causes

Water pollution can come from a variety of sources. Pollution can enter water directly, through both legal and illegal discharges from factories, for example, or imperfect water treatment plants. Spills and leaks from oil pipelines or hydraulic fracturing (fracking) operations can degrade water supplies. Wind, storms, and littering—especially of plastic waste —can also send debris into waterways.

Thanks largely to decades of regulation and legal action against big polluters, the main cause of U.S. water quality problems is now " nonpoint source pollution ," when pollutants are carried across or through the ground by rain or melted snow. Such runoff can contain fertilizers, pesticides, and herbicides from farms and homes; oil and toxic chemicals from roads and industry; sediment; bacteria from livestock; pet waste; and other pollutants .

Finally, drinking water pollution can happen via the pipes themselves if the water is not properly treated, as happened in the case of lead contamination in Flint, Michigan , and other towns. Another drinking water contaminant, arsenic , can come from naturally occurring deposits but also from industrial waste.

Freshwater pollution effects

Water pollution can result in human health problems, poisoned wildlife, and long-term ecosystem damage. When agricultural and industrial runoff floods waterways with excess nutrients such as nitrogen and phosphorus, these nutrients often fuel algae blooms that then create dead zones , or low-oxygen areas where fish and other aquatic life can no longer thrive.

Algae blooms can create health and economic effects for humans, causing rashes and other ailments, while eroding tourism revenue for popular lake destinations thanks to their unpleasant looks and odors. High levels of nitrates in water from nutrient pollution can also be particularly harmful to infants , interfering with their ability to deliver oxygen to tissues and potentially causing " blue baby syndrome ." The United Nations Food and Agriculture Organization estimates that 38 percent of the European Union's water bodies are under pressure from agricultural pollution.

Globally, unsanitary water supplies also exact a health toll in the form of disease. At least 2 billion people drink water from sources contaminated by feces, according to the World Health Organization , and that water may transmit dangerous diseases such as cholera and typhoid.

Freshwater pollution solutions

In many countries, regulations have restricted industry and agricultural operations from pouring pollutants into lakes, streams, and rivers, while treatment plants make our drinking water safe to consume. Researchers are working on a variety of other ways to prevent and clean up pollution. National Geographic grantee Africa Flores , for example, has created an artificial intelligence algorithm to better predict when algae blooms will happen. A number of scientists are looking at ways to reduce and cleanup plastic pollution .

There have been setbacks, however. Regulation of pollutants is subject to changing political winds, as has been the case in the United States with the loosening of environmental protections that prevented landowners from polluting the country’s waterways.

Anyone can help protect watersheds by disposing of motor oil, paints, and other toxic products properly , keeping them off pavement and out of the drain. Be careful about what you flush or pour down the sink, as it may find its way into the water. The U.S. Environmental Protection Agency recommends using phosphate-free detergents and washing your car at a commercial car wash, which is required to properly dispose of wastewater. Green roofs and rain gardens can be another way for people in built environments to help restore some of the natural filtering that forests and plants usually provide.

Related Topics

• WATER POLLUTION
• ENVIRONMENT AND CONSERVATION
• FRESH WATER
• GROUNDWATER
• WATER QUALITY
• WATER RESOURCES

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Water Pollution: “Dal Lake a Case Study”

• Conference paper
• First Online: 29 April 2022
• Cite this conference paper

• Shabina Masoodi 4 ,
• Lone Jaseem Saleem 4 ,
• Sadiya Majeed 4 ,
• Aflak Rashid Wani 4 ,
• Mohammad Furqan 4 &
• Rasim Javeed Banday 4  

497 Accesses

1 Citations

Dal lake is one of the famous freshwater lakes of Jammu & Kashmir and is rightly called as “Liquid jewel “in the heart of capital city Srinagar.

Over the years the lake is under serious anthropogenic activities which has resulted in pollution of the lake threatening its health and ecology. Despite many consultancies were engaged for the conservation of this lake yet the trophic condition of the lake has not shown any significant progress nor the water quality has improved.

In this paper an attempt has been made to assess the measures taken for its conservation, study the current Ecological status of the lake and reasons for the failure of the Conservation of the lake coupled with suggestive measures.

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MRD Kundangar, SabhaulSalim and Adnan Abubakr. Deweeding practices in Dal lake and their impact assessment Studies National Environment and Pollution Technology. vol.2, no.1. Pp 95–103, 2003.

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M. R.D. Kundangar and Adnan Abubakr. Dal Lake Conservation Project: An Appraisal 2021- 143 —M.R.D. Kundangar, Adnan Abubakr Ecosystem and Management. editors: Dr. Ashwani Wanganeoon Dr. Rajniwanganeookaul.

Qazi Tanveer, Houseboat sanitation and its impact on Dal lake Ecology. M tech. Dissertation. Punjab Technical University, 2017)

Shabina Masoodi & MRD Kundangar. Engineering interventions for Dal Lake conservation in Global Sustainibility Transitions: impacts and innovations. Editor, Prof. (Dr.) Govind Chandra Mishra. 2014.

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Acknowledgement

Words at our command are not adequate in spirit and form to meet the ends of justice in matter of expression of profound sense of gratitude and indebtedness to Er Shabeena Masoodi and especially Dr MRD Kundangar, Former Director, Lakes & Waterways Development Authority, J&K for encouraging, material guidance, valuable suggestions and objective approach towards work which enables us to accomplish this paper.

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Masoodi, S., Saleem, L.J., Majeed, S., Wani, A.R., Furqan, M., Banday, R.J. (2022). Water Pollution: “Dal Lake a Case Study”. In: Kanwar, V.S., Sharma, S.K., Prakasam, C. (eds) Proceedings of International Conference on Innovative Technologies for Clean and Sustainable Development (ICITCSD – 2021). Springer, Cham. https://doi.org/10.1007/978-3-030-93936-6_54

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Bottled water, tap water and household-treated tap water–insight into potential health risks and aesthetic concerns in drinking water

Roles Conceptualization, Formal analysis, Investigation, Methodology, Project administration, Supervision, Validation, Writing – original draft

Affiliation SimpleLab, Inc. Berkeley, California, United States of America

Roles Data curation, Investigation, Writing – review & editing

Affiliations SimpleLab, Inc. Berkeley, California, United States of America, Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio, United States of America

Roles Formal analysis, Visualization, Writing – review & editing

Roles Conceptualization, Formal analysis, Funding acquisition, Methodology, Project administration, Supervision, Writing – original draft

* E-mail: [email protected]

• Samantha E. Bear, 
• Talya Waxenberg, 
• Charles R. Schroeder, 
• Jessica J. Goddard

• Published: September 4, 2024
• https://doi.org/10.1371/journal.pwat.0000272
• Reader Comments

Understanding drinking water quality at the point-of-use across a range of consumer options is essential for designing effective public health interventions in the face of deteriorating source waters and complex contaminant mixtures. This is especially pressing as the popularity of tap water alternatives like bottled water and household treatment increases, yet this data is largely missing from the academic literature and policy discussions. This study presents one of the first evaluations of water quality comparing three common consumer drinking water options in the nine county San Francisco Bay Area with a survey of 100 analytes in 100 bottled water samples, 603 tap water samples, and 111 samples of household-treated tap water. Analytes measured included general water quality characteristics, metals, other inorganics, volatile organic compounds (including disinfection byproducts), and three microbial indicator species in bottled water only. Samples were evaluated to assess potential taste, odor, and color issues, as well as potential health risks by calculating cumulative toxicity quotients to reflect the additive toxicity of chemical mixtures. All three drinking water options had potential health risks, primarily driven by the presence of trihalomethanes (contributing from 76.7 to 94.5% of the total cumulative toxicity across the three drinking water options). While tap water had the highest potential toxicity among the three drinking water options, results suggest that household-scale treatment may reduce the potential for aesthetic issues and health risks of tap water.

Citation: Bear SE, Waxenberg T, Schroeder CR, Goddard JJ (2024) Bottled water, tap water and household-treated tap water–insight into potential health risks and aesthetic concerns in drinking water. PLOS Water 3(9): e0000272. https://doi.org/10.1371/journal.pwat.0000272

Editor: Inderjeet Tyagi, ZSI: Zoological Survey of India, INDIA

Received: March 5, 2024; Accepted: July 31, 2024; Published: September 4, 2024

Copyright: © 2024 Bear et al. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All data required to reproduce the results and statistics of this study are provided in the SI or are readily available for download. Individual sample results were de-identified and anonymized and are available in Supporting Information Table S8.

Funding: The authors received no specific funding for this work.

Competing interests: The authors have declared that no competing interests exist.

Abbreviations: BW, bottled water; HTTW, household-treated tap water; TW, tap water; TQ, toxicity quotient; POU, point-of-use; POE, point-of-entry; EPA, Environmental Protection Agency; FDA, Food and Drug Administration; SOQ, Standards of Quality; PET, polyethylene terephthalate; VOC, volatile organic compound; DBP, disinfection byproduct; THM, trihalomethane

1. Introduction

Tap water quality issues are on the rise in the US. Deteriorating infrastructure [ 1 ], climate change pressures on source waters [ 2 , 3 ], increasingly complex chemical mixtures in the environment [ 4 , 5 ], governance failures [ 6 ], and low technical, financial and managerial capacity have led to compounding pressures on water systems. Lead, arsenic, nitrate, uranium and bacterial contaminants are all federally regulated and frequently found in violation of drinking water standards across the US [ 7 – 9 ]. Where tap water quality is in question or consumers distrust their water system for other reasons, people turn to alternative sources like bottled water [ 10 ] and household-scale treatment of their tap water [ 11 – 13 ]. Bottled water use is growing rapidly, with per capita consumption in the US having increased from 27.8 gallons per person per year in 2010 to 45.2 gallons per person per year in 2020 [ 14 ]. Household water treatment is a 2.09-billion-dollar market in the US [ 15 ]. While these alternatives to tap water are attracting a growing share of tap water consumers, insight into their water quality implications is scant. Lack of adequate monitoring data across consumer options hinders policymakers’ ability to identify effective economic and public health interventions to address tap water quality issues and public health more broadly. This study offers a comparative analysis of bottled water, household-treated tap water, and tap water quality using a unique dataset to evaluate potential organoleptic and toxicity trade-offs among drinking water options for households in the San Francisco Bay Area. The resulting analysis offers insight into multiple toxicity mitigation priorities for improving drinking water quality.

There is a widespread perception that bottled water is “pure” and free of contaminants, due in part to misleading marketing [ 16 – 18 ]. Additionally, aesthetic properties of tap water like taste and odor have been documented to impact people’s perception of tap water safety [ 19 – 21 ], potentially driving people toward alternatives like bottled water [ 22 , 23 ]. However, a wide range of contaminants have been identified in US bottled water due to contamination from source water, bottle processing, or packaging material leachate [ 16 ]. Contaminants detected in bottled water products include bacteria, various heavy metals (including lead), volatile and semi-volatile organic contaminants (including phthalates), disinfection byproducts, radiological elements, microplastics, and various PFAS compounds [ 24 – 31 ].

Households seeking improved tap water also turn to point-of-entry (POE) and point-of-use (POU) treatment of delivered tap water. In the international context, concerns about appropriate technology selection and whether systems are maintained appropriately are central to understanding household-treated tap water quality [ 32 ]. In the US, household behaviors with treatment equipment and their impact on water quality are unknown. Evidence suggests that people purchase treatment units in response to publicized water quality contamination events or concerns about the taste, odor and color of their water [ 23 ], rather than in response to targeted testing to characterize on-site contamination. While perceptions can correlate with contaminant occurrence, there are many contamination issues that have no organoleptic effects. As such, household-treated tap water poses an exposure risk if treatment is not tailored to a household’s water quality.

The existing literature on drinking water quality is not typically geared toward understanding differences among drinking water options at the household level primarily due to a lack of adequate data. Monitoring and reporting for water system-supplied tap water quality is limited due to a focus on regulated contaminants that are not monitored at the tap (except for lead). Previous studies of tap water quality have been extensive in the contaminants they evaluate but have smaller sample sizes (≤45) [ 4 , 33 – 35 ]. In a study of public tap water and private well supplies in North and South Dakota, the authors concluded that public monitoring data beyond water system compliance is needed “to inform consumer POE/POU treatment decisions’’ across the US [ 35 ]. However, while household-treated tap water quality has been studied internationally [ 36 ], to our knowledge, there are no large-scale studies of household-treated tap water in the US. Also, while numerous bottled water quality analyses exist, they rarely represent the quality of a “typical” bottled water purchase based on the market share of products in a given region. Thus, while these studies indicate potential contamination across the different water sources, a comparative picture of water quality across these three consumer options is lacking.

To our knowledge, this study is one of the first large sample size water quality comparisons among consumer drinking water options and the first U.S. based study of household-treated tap water. One hundred bottled water products (across 89 brands) were collected and tested, and this data was compared to 714 tap water samples across the San Francisco Bay Area collected by households using a consumer test kit product–including 603 direct tap water samples and 111 samples with follow-up household water treatment. The bottled water sample set reflects a “typical” bottled water purchase in the Bay Area, whereas the 714 tap water samples are part of a citizen-science dataset (a convenience sample). One hundred analytes, spanning metals, volatile organic compounds, and common water quality parameters, were surveyed in all three sources, as well as three bacteriological indicators in bottled water.

Potential risks to human health were evaluated using a cumulative toxicity framework in which the concentrations of analytes in a sample were compared to health benchmarks, and potential organoleptic effects were also identified via comparison with aesthetic benchmarks [ 37 , 38 ]. The findings highlight potential drivers of water source preference with respect to organoleptics, as well as drivers of cumulative toxicity, for all three drinking water options. Tractable recommendations are offered for consumers and policymakers aspiring to improve POU tap water quality in the face of complex environmental and financial trade-offs among drinking water options.

To compare the quality of drinking water options in the Bay Area, this study leverages a primary dataset of bottled water samples and a unique secondary dataset of (unpaired) tap water samples and household-treated tap water samples. Each sample was evaluated for 100 analytes, many with possible organoleptic effects and/or potential toxicity. A dataset of aesthetic and health benchmarks for drinking water analytes was compiled from engineering, toxicology, and public health literature to identify concentrations of concern. These data were combined to analyze levels of exceedance and potential toxicity across all three drinking water options. This section first presents the methods of sample collection and laboratory analysis used in each dataset, followed by the comparative data analysis approach.

2.1. Bottled water sample selection and collection

A sample design was developed to represent a “typical” bottled water (BW) purchase for consumers in the San Francisco Bay Area nine county region (Alameda, Contra Costa, Marin, Napa, San Francisco, San Mateo, Santa Clara, Solano, and Sonoma counties). A representative sample set was considered to be one that approximately mimicked the market share of BW products sold in the US in 2020 by Food and Drug Administration (FDA) category [ 39 ]. FDA categories are based on the source water and/or water treatment used and include “spring water”, “artesian water”, “mineral water”, “well water” and “purified water” [ 40 ]; see Table A in S1 File for sample details. The final sample included 100 BW products encompassing 89 brands (Table A in S1 File ) purchased from 80 stores across the nine-county region (Fig A in S1 File ). Forty six percent of products were from groundwater sources with no specific treatment requirements from FDA, while another 46% of products were from various sources (often unspecified) with FDA treatment requirements (referred to as “purified”, including those marketed as “distilled”). The remaining 8% of products did not meet FDA requirements for any official bottled water categories.

All 100 products were purchased between July 12 th and July 28 th , 2022. They were sent, unopened, to the Microbac Laboratories facility in Dayville, CT for sampling and analysis within one week of purchase.

2.2. Tap water and household-treated tap water sample selection and collection

Tap water and household-treated tap water samples were selected from a secondary data set obtained from SimpleLab, Inc of individual samples taken over time (as opposed to repeat samples at specific locations). All samples in this dataset were from water system supplied households in the nine county San Francisco Bay Area that purchased water quality testing kits from Tap Score TM (a product of SimpleLab, Inc.) between September 17 th , 2020 and August 16 th , 2022 (Fig B in S1 File ). Selected tap water (TW) and household-treated tap water (HTTW) samples were limited to those with the complete set of 100 analytes analyzed in the BW samples to enable a direct comparison. Samples were categorized as HTTW if residents reported using in-home water treatment devices (excluding water softeners), and as TW if not. HTTW samples and TW samples are not paired samples and therefore contaminant removal efficiencies of household treatment choices could not be calculated. The final dataset includes 714 samples: 603 TW samples and 111 HTTW samples. Seventy-seven percent of water systems supplying the TW and HTTW samples in this study rely on surface water as the primary water source, though nearly all have some groundwater-reliant facilities (see Table F in S1 File for summary of water system treatment and water source characteristics).

For sample collection, Tap Score TM test kits included sample containers and detailed instructions regarding appropriate sampling technique. Two sample containers were provided: one 250 mL HDPE bottle for a first draw sample filled to the shoulder (for analysis of general chemical characteristics, metals and other inorganics), and one 40 mL clear glass VOA vial containing 25 mg of ascorbic acid for a fully flushed sample with no headspace (for volatile organic compound analysis).

2.3. Laboratory analyses

All samples across the two datasets were analyzed at accredited, commercial laboratories using EPA-approved methods for 100 select analytes, including general water quality characteristics (e.g., pH, hardness, total dissolved solids, etc.) and chemical constituents (Tables B and C in S1 File ). Analytes were selected based on the contaminants most frequently tested among households that used Tap Score TM . BW was further analyzed for three microbiological indicators (total coliform, E . coli , and total HPC); these indicators were not measured in TW or HTTW samples as they are not included in the standard water testing package. Only quantitative data (> method reporting limits) was reported and considered a detection.

2.4. Data analysis

Sample results were assessed individually for potential toxicity and aesthetic concerns, as well as cumulatively within samples and across drinking water options. Anonymized analytical sample results are provided in Table J in S1 File .

2.4.1. Health and aesthetic benchmarks.

To evaluate potential health risks and organoleptic impacts from the analytes measured, a list of health and aesthetic benchmark values was developed for each analyte. If an analyte has no known impact on human health and/or the aesthetic experience of drinking water, or research is insufficient for determining an impact, no benchmark was assigned.

Health benchmarks were aggregated from various public health agencies and governmental bodies. These benchmarks reflect concentrations of contaminants below which no known non-cancer impacts are expected over a lifetime of exposure (typically toxicity to specific organ systems), or concentrations that result in specific cancer risk levels over a lifetime of exposure (from 10 −4 to 10 −6 ). Similar to previous studies, the lowest health benchmark available for each analyte was used in order to evaluate all analytes against the most health-protective value available [ 24 , 33 – 35 , 37 , 38 , 41 ] (Table D in S1 File ).

Similarly, aesthetic benchmarks were derived by creating a database of benchmark concentrations for analytes that have been associated with organoleptic effects like off tastes or odors, or discoloration, and the lowest concentration among benchmarks was selected as the aesthetic benchmark. These benchmarks were gathered from institutional, governmental and academic sources (Table E in S1 File ).

2.4.2. Cumulative toxicity quotient calculations.

Frameworks for cumulative health impacts assume health risks from exposures are additive and they guide many public health assessments of drinking water quality [ 42 – 44 ]. Without information on duration of exposure, volume of water consumed, or personal susceptibility, health risks or effects cannot be fully characterized. Instead, detected concentrations were compared to benchmarks that indicate potential toxicity of an exposure given (typically) lifetime exposure duration and common assumptions about relative source contributions across exposure pathways. The resultant ratio is known as a toxicity quotient ( TQ ).

2.4.3. Statistical analyses.

Welch’s one-way analysis of variance (ANOVA) was conducted using the rstatix package in R to evaluate difference of means among ∑ TQs in the three sample groups [ 47 , 48 ]. Welch’s test accounts for unbalanced groups and unequal variances among groups. Because means can be sensitive to outliers, a sensitivity analysis was performed removing outliers defined as ∑ TQs greater than 75 th percentile plus 1.5 times the interquartile range for all three sample groups. The null hypothesis was that there was no significant difference in mean ∑ TQs among the three sample groups. Where Welch’s ANOVA was significant, it was followed up with nonparametric Games-Howell posthoc tests to evaluate differences in means among the three sample groups.

3. Results and discussion

A wide variety of contaminants were detected in samples from all three drinking water options, including many with the potential to impact human health or the odor, taste, or color of drinking water. The presence of contaminant mixtures in these samples is consistent with previous studies of BW [ 24 , 30 ] and TW quality in California [ 9 , 49 – 51 ]. Contaminant level summary statistics by drinking water option are shown in Table G in S1 File .

3.1 Exposure-benchmark comparison: Aesthetic benchmarks

Potential aesthetic issues were identified in samples from all three drinking water options, but higher concentrations of contaminants with aesthetic benchmarks were detected in TW and HTTW compared with BW. Forty-one of the 100 analytes measured have aesthetic benchmarks. Twenty of these 41 analytes were detected in at least one sample, including volatile organic compounds (VOCs), metals, other inorganics, and general water quality characteristics such as hardness and total dissolved solids ( Fig 1 ).

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Detected concentrations (in μg/L) of analytes with aesthetic benchmarks in bottled water (blue, n = 100), household-treated tap water (green, n = 111) and tap water (purple, n = 603) for contaminants that were detected in more than one water source (a) and those detected in only one water source (b). Percent of samples in which analyte was detected on the right. Concentrations are plotted on a log-scale to allow for legibility in comparing concentrations among BW, TW, and HTTW.

https://doi.org/10.1371/journal.pwat.0000272.g001

Across BW samples, six analytes exceeded their aesthetic benchmarks, as compared with eight and 12 in HTTW and TW samples, respectively (Fig C in S1 File ). At least one aesthetic benchmark exceedance was found in 24% (n = 24/100), 44% (n = 49/111), and 41% (n = 246/603) of BW, HTTW, and TW samples, respectively. The concentrations of analytes were generally similar among water sources, with some exceptions where BW concentrations were lower (including zinc, copper, fluoride, and bromoform).

Calcium was the only analyte to exceed aesthetic benchmarks at a higher proportion in BW than in HTTW and TW (4% of results in exceedance in BW versus 0% for both HTTW and TW). Aesthetic exceedances across water sources were largely from analytes that impact taste and staining–such as metals (aluminum, copper, iron, manganese and, for TW only, zinc), magnesium, and sodium (Fig C in S1 File ). For example, magnesium and sodium exceeded taste thresholds for bitter or salty flavors in all water sources. The benchmark for magnesium was exceeded in 16% (n = 16/100), 33% (n = 37/111) and 29% (n = 173/603) of BW, HTTW and TW samples, respectively, and the aesthetic benchmark for sodium was exceeded in 10% (n = 10/100), 19% (n = 21/111) and 20% (n = 122/603) of BW, HTTW and TW samples, respectively. These elements are naturally occurring, likely present in all sources due to natural processes, and are not fully removed via many at-home treatment processes–sodium, in fact, may be added to water that is softened via an ion exchange water softener [ 52 , 53 ].

Iron and copper both exceeded taste thresholds in TW and HTTW in higher proportions than in BW. The aesthetic benchmark for iron was exceeded in 2% (n = 2/100), 4% (n = 4/111) and 10% (n = 62/603) of BW, HTTW and TW samples, respectively, and that of copper was exceeded in 0%, 7% (n = 8/111) and 5% (n = 30/603) of BW, HTTW and TW samples, respectively. These metals can enter drinking water via water distribution lines and household plumbing and fixtures [ 54 , 55 ], all of which BW mostly avoids. These results are consistent with studies showing that aesthetic impacts like off-tastes are common in TW and a primary reason people turn to BW [ 19 – 21 ].

3.2 Exposure-benchmark comparison: Health benchmarks

Analytes with potential health risks were detected in samples from all three drinking water options in exceedance of health benchmarks. Eighty-four of the 100 contaminants tested in all samples have health benchmarks. Forty of these 84 contaminants, including disinfection byproducts, other VOCs, metals, and other inorganics, were detected in at least one sample ( Fig 2 ). Seventeen health benchmarks were exceeded in both BW and HTTW, and 25 were exceeded in TW (Fig D in S1 File ). At least one health benchmark was exceeded in 53% (n = 53/100), 61% (68/111), and 98% (n = 590/603) of BW, HTTW, and TW samples, respectively. These differences likely stem, in large part, from treatment and source water effects across samples.

Detected concentrations (in μg/L) of analytes with health benchmarks in bottled water (blue, n = 100), household-treated tap water (green, n = 111) and tap water (purple, n = 603) for contaminants that were detected in more than one water source (a) and those detected in only one water source (b). For panel (b), one very high value for tin obscures the concentrations of other contaminants and therefore an axis break is plotted showing observations between 0 μg/L and 100 μg/L, and then the very high value at 5,110 μg/L. Percent of samples in which analyte was detected are indicated on the right. Concentrations are plotted on a log-scale to allow for legibility in comparing concentrations among BW, TW, and HTTW.

https://doi.org/10.1371/journal.pwat.0000272.g002

Fewer health benchmark exceedances in BW likely reflects both the high degree of treatment of the 46 purified products (44 of which employed either distillation or reverse osmosis, see Table A in S1 File ) and the overall high integrity of source waters for the 46 groundwater-sourced products. Specific treatment is not required by the FDA for groundwater-sourced BW products as long as they meet quality standards [ 40 ]; only 11 of 46 groundwater-sourced BW products listed any treatment, which included filtration and disinfection (either via UV or ozone). On the other hand, nearly all TW and HTTW samples in this study were taken from water systems that rely on conventional drinking water treatment (coagulation, flocculation, sedimentation, filtration, and disinfection) (Table F in S1 File ). Conventional treatment is largely adequate to meet regulatory standards, but not necessarily effective in reducing contaminant concentrations below health benchmarks or removing them entirely.

While 98% of TW samples had at least one health benchmark exceedance, 61% of HTTW samples had an exceedance, indicating that some treatment effect is likely. Specific treatment information for HTTW samples is not comprehensive in the dataset, but 88 out of 111 samples reported using carbon-based filters and/or reverse osmosis systems, which likely contributed to the lower overall exceedances. However, the proportion of health benchmark exceedances remaining in HTTW samples indicates that barriers still persist for achieving health risk reduction using at-home treatment. For example, household treatment technologies are often purchased in the absence of water testing to identify appropriate technologies, and effective contaminant removal can be hindered by technology selection and improper maintenance.

3.2.1 Trihalomethanes.

The trihalomethanes (THMs) chloroform, bromodichloromethane and dibromochloromethane were three of the contaminants with the most frequent health benchmark exceedances across all samples tested (Fig D in S1 File ). THMs are formed when chlorine disinfectant reacts with natural organic matter in source waters, which is why mitigation strategies employed by water utilities largely focus on controlling precursors to THMs (i.e. monitoring total organic carbon) [ 56 ]. The proportion of samples with THM exceedances was highest in TW, followed by BW and HTTW. There has been growing concern about disinfection byproducts (DBPs) in drinking water [ 57 – 59 ], which is consistent with the detections of these chlorinated DBPs. Health effects of the three THMs include developmental/reproductive effects, liver toxicity, and an increased risk of cancer [ 60 – 63 ]. THMs were the only contaminants analyzed in this study that exceeded the limits guiding their regulation. Four THMs are regulated as a group called total THMs: chloroform, bromoform, bromodichloromethane and dibromochloromethane. Eight BW samples (8%) exceeded the California BW quality regulatory limit of 10 μg/L for total THMs (which is lower than the FDA’s SOQ of 80 μg/L) [ 64 ], while 13 TW samples (2%) exceeded the federal maximum contaminant level of 80 μg/L [ 65 ]. No HTTW samples exceeded either of these regulatory limits. However, individual THMs exceeded their health protective benchmarks–ranging from 0 to 0.22 μg/L (Table D in S1 File )–in all three drinking water options. For example, chloroform exceeded its health benchmark in 32% of BW samples (n = 32/100), 25% of HTTW samples (n = 28/111) and 89% of TW samples (n = 534/603). Exceedances (equal to detections) in BW were similar to the proportion of detections in Bradley et al. [ 24 ]. Most purified BW products employed reverse osmosis as the primary treatment, which has been shown to incompletely remove THMs [ 66 ]. Because regulatory limits for THMs are so much higher than health benchmarks, it is likely that all drinking water options will continue to present health risk while remaining in compliance with regulations.

The high proportion of THM detections in TW is consistent with violation trends in California [ 49 ] and reported concentrations in Bay Area water systems [ 51 ]. Surface water typically has higher levels of organic matter (i.e., THM precursors) than groundwater and, as such, water systems primarily reliant on surface water are at higher risk of THM formation when using chlorine as a disinfectant [ 63 ]. The vast majority of TW and HTTW samples (92%) were taken by households in water systems reliant on surface water as their primary source (of these systems, 52% have facilities that also rely on at least one groundwater source). Moreover, 60% of these samples are from households in water systems that use chlorine or chloramine as a disinfectant (Table F in S1 File ). Taken together, the impact of THMs on potential toxicity across water sources is unsurprising and reflects a significant challenge for water systems reliant on surface water and chlorination.

3.2.2 Metals.

Contamination due to metals is another well-known drinking water safety challenge, often caused by corrosion of pipes and fixtures and/or inadequate corrosion control in the presence of corrosive source waters [ 55 , 67 ]. Lead was detected (and exceeded its health benchmark of 0) in samples from all three drinking water options, though only in one BW sample. In contrast, lead was detected in 30% (n = 33/111) of HTTW samples and 51% (n = 306/603) of TW samples. The proportion of detections in BW is lower than that reported by Bradley et al. [ 24 ], who found lead in five out of 30 samples (17%) but had lower method detection limits than this study. Lead is a persistent challenge due to aging infrastructure across the US, and exposure to lead can cause adverse neurological, developmental, learning and behavioral effects, especially in children [ 68 – 70 ]. The higher proportion of exceedances found in HTTW and TW is consistent with the potential for contamination from the distribution system and on-premises plumbing.

Other metals that exceeded health benchmarks have a variety of potential sources, including on-site fixtures and faucets subject to less stringent regulations than lead in pipes (e.g. copper and nickel), and source waters (arsenic, uranium, cadmium, cobalt). Copper and nickel were detected in samples from all drinking water options and exceeded their health benchmarks in 7% to 14% of HTTW and TW samples, but neither exceeded their benchmarks in BW. A number of geogenic elements also exceeded health benchmarks in samples from all drinking water options, consistent with previous studies [ 24 , 35 , 49 , 51 ]. Uranium exceeded its health benchmark in 6% of BW samples (n = 6/100), as compared with 2% in HTTW (n = 2/111) and TW (n = 13/603). Uranium has been shown to cause kidney and osteo- toxicity in human and animal studies, as well as adverse female reproductive and developmental effects in animal studies [ 71 , 72 ]. Arsenic was detected in a similar proportion of samples in BW and HTTW samples (7% or n = 7/100, and 8% or n = 9/111, respectively), and in a lower proportion of TW samples (3% or n = 16/603). Exposure to arsenic in drinking water has been shown to increase the risk of cancer, as well as cause adverse dermal and blood system impacts [ 73 , 74 ].

Source water is likely the primary driver of these geogenic exceedances. All uranium detections in BW were in groundwater-sourced products (13% of groundwater-sourced BW products; n = 6/46). Similarly, arsenic exceeded its health benchmark in groundwater-sourced BW products only (15%, n = 7/46). Bradley et al. [ 24 ] similarly found uranium and arsenic in groundwater-sourced BW, but at substantially higher proportions (74% and 87% for uranium and arsenic, respectively) using lower detection limits. The lower proportion of these contaminants in HTTW and TW is consistent with the fact that the majority of tap water samples were sourced from surface water, with a smaller proportion of facilities reliant on groundwater sources (Table F in S1 File ).

3.2.3 Other VOCs.

In BW, additional detections and exceedances suggest that bottle production and processing may play a role in water quality. Two petroleum-derived compounds–benzene and toluene were detected in BW only. One benzene detection was in exceedance of the health benchmark, and all 5 toluene detections were below the health benchmark. One possibility is that these contaminants were introduced to bottled water products during processing [ 75 ].

3.2.4 Bacteria.

The microbiological indicators total coliform, E . coli , and total heterotrophic bacteria (total HPC) were evaluated in BW samples only. While no E . coli or total coliform were found in BW samples, heterotrophic bacteria were detected in 43% of BW samples (Fig E in S1 File ). Heterotrophic bacteria are not considered good indicators of pathogenic bacteria [ 76 ], but total HPC serves as an indicator of overall sterility. These findings corroborate previous studies identifying HPC in BW, which found detections in 30% - 71% of samples [ 24 , 27 ]. While tap water samples are likely to have HPC as well because of its ubiquitous presence in the environment, these findings are particularly interesting in BW because of marketing claims about the purity of BW.

3.3 Cumulative toxicity quotients

A cumulative toxicity quotient (∑ TQ ) was calculated for each sample to assess overall potential toxicity by summing detected contaminant concentrations divided by their health benchmarks. Fig 3 plots cumulative toxicity quotients for samples of each drinking water option in comparison with the benchmark equivalent concentration (∑ TQ = 1).

The red line indicates the benchmark equivalent concentration (∑ TQ = 1). Posthoc test results with p-values adjusted for multiple hypothesis testing shown above boxplots to indicate significant difference in group means between pairs at p <0.0001 (****).

https://doi.org/10.1371/journal.pwat.0000272.g003

Eighty percent (n = 80/100), 97% (n = 108/111), and >99% (n = 602/603) of BW, HTTW and TW samples, respectively, exceeded the effects-screening-level of concern, while 54% (n = 54/100), 83% (n = 92/111), and >99% (n = 598/603) of BW, HTTW and TW samples, respectively, exceeded the benchmark equivalent concentration. This indicates a high potential for health risk due to lifetime consumption of water from each of the drinking water options tested, with the highest potential hazard posed by TW and the lowest by BW. These ∑ TQ results agree with those of prior studies of both nationwide POU TW and BW [ 33 – 35 , 41 ], though Bradley et al. [ 24 ] saw a higher proportion of effects-screening-level and benchmark equivalent concentration exceedances for BW. The mean (and standard deviation) of ∑ TQ was 12.0 (±23.5), 20.3 (±39.6), and 130.3 (±75.4) in BW, HTTW, and TW, respectively, indicating the disproportionately higher potential toxicity of TW compared with BW and HTTW (Table H in S1 File ).

Drinking water option was significantly associated with cumulative toxicity quotient outcomes using Welch’s one-way ANOVA (F = 502.44, p<0.0001) to account for unequal variance [ 77 ] (Tables A and B in S1 Text ). Effect size as measured by omega-squared was large (0.77; Table C in S1 Text ). This finding was robust to a sensitivity analysis removing outliers. Overall, Games-Howell posthoc tests indicated the average TW sample had significantly higher potential toxicity than that of both HTTW and BW samples (p<0.0001), whereas the average HTTW and BW sample had no significant difference in mean toxicity quotients ( Fig 3 ; Table D in S1 Text ). While mean differences were insignificant between BW and HTTW, the variability of HTTW ∑ TQs was greater than that of BW ∑ TQs (Table H in S1 File ), as indicated by a wider interquartile range (1.3–18.4) compared with that of BW (0.2–12.2). This suggests that HTTW had slightly more variability in potential toxicity at a sample level. This likely reflects the range of technologies applied to the HTTW samples, which included sediment filters, carbon-based filters, reverse osmosis, ion exchange, distillation, KDF filters, UV disinfection and unspecified filtration.

Individual contaminant TQs across samples indicate that, at the sample level, a diverse range of contaminants may be responsible for the potential toxicity of any individual sample (Figs F-H in S1 File ), underscoring the importance of sample-level toxicity assessments to consider exposure risks at a household-level. However, when contaminants are identified for their percent contribution to the overall potential toxicity of a drinking water option ( Fig 4 ; Table I in S1 File ), toxicity mitigation strategies for broader public health improvements can be prioritized, as discussed in the following section.

https://doi.org/10.1371/journal.pwat.0000272.g004

Consistent with the exceedance results in Section 3.2 and findings in Bradley et al. [ 24 ], THMs–driven primarily by chloroform–were responsible for most of the potential toxicity for all three drinking water categories– 79.4%, 76.7%, and 94.5% for BW, HTTW and TW, respectively ( Fig 4 ; Table I in S1 File ). Addressing chloroform and THMs generally is important across all drinking water options, but Fig 4 (and Table I in S1 File ) illustrates that 94.5% of potential toxicity as determined by the 100 analytes evaluated in TW samples would be addressed at the tap by treating THMs (0.87% of total potential toxicity is contributed by bromodichloromethane which is displayed in the “Other” group in Fig 4 ).

The remaining risk for TW and HTTW was primarily driven by lead, with contributions from other metals (including nickel, copper, cadmium and cobalt), geogenic elements (arsenic and uranium) and fluoride for HTTW, while the remaining risk for BW was driven by geogenic elements (including lithium, uranium, boron and arsenic). In the case of HTTW, potential toxicity was composed of a wider range of compounds–likely because many household treatment technologies are mitigating trihalomethanes and thus other unaddressed contaminants drive overall toxicity.

3.4 Implications for toxicity mitigation

Taken together, the absolute exceedances and cumulative toxicity results have a range of implications for consumer choice among BW, HTTW and TW. First, analytes impacting taste thresholds exceeded benchmarks in TW and HTTW samples more than in BW samples, supporting evidence that aesthetic differences between TW and BW may drive consumers toward BW. However, cumulative toxicity results indicate that BW is not free from exposure risk despite emphatic marketing otherwise. Though not addressed in this study, the environmental and financial burden of BW is also substantial when compared with those of HTTW and TW–environmental impacts of BW are orders of magnitude greater than that of TW [ 78 , 79 ] and the price of BW exceeds that of HTTW or TW by thousands of dollars per year [ 17 ]. While BW may be preferable for a temporary period where TW is declared unsafe, HTTW is likely a more affordable and sustainable option where aesthetic issues and potential toxicity risk persist in TW [ 80 ]. This is supported by the finding that the difference in mean cumulative potential toxicity was insignificant between HTTW and BW.

While HTTW has the potential to mitigate certain contaminants, potential toxicity was still identified in HTTW samples. This underscores the importance of technology selection tailored to POU water quality and ongoing user maintenance to ensure HTTW efficacy. Fig 4 demonstrates the potential mitigating effect of household treatment on disinfection byproducts relative to TW and illustrates the diverse range of contaminants that contribute to the toxicity of these samples overall. The wide range of contaminants found in HTTW samples would likely be reduced if treatment technology were chosen in accordance with POU water quality. Further research to support user compliance and maintenance of treatment devices, perhaps in partnership with utilities, is warranted.

Third, TW and HTTW samples had higher exceedances and potential toxicity than BW from metals commonly used in distribution systems, plumbing, and fixtures. For example, lead was detected in 51% of TW samples and 30% of HTTW samples (but only one BW sample), and contributed 2.9% and 6.6% of overall toxicity to TW and HTTW, respectively ( Fig 4 ). Lead is a well-studied problem that has garnered significant policy response–the recently proposed Lead & Copper Rule Improvements would require utilities to replace all lead service lines within 10 years [ 81 ]. While this should reduce lead levels in TW and HTTW, it has been over 30 years since the original Lead & Copper Rule was established [ 54 ] and almost 10 years since the Flint, MI water crisis. Policy can be slow to address even well-understood contaminants, and other metals–like cobalt, nickel, and cadmium detected in TW and HTTW samples–have diverse sources that may be more challenging to mitigate through targeted policies. In such cases, properly designed, targeted household-scale treatment may be an effective intervention to reduce toxicity further than currently possible with drinking water standards. Some cities have begun to implement this, for example Denver Water delivered free pitcher filters to households to support their lead remediation goals [ 82 ].

Finally, targeted treatment for THMs would reduce the risk profile for all drinking water options, but would have the greatest impact in TW. Given the prevalence of surface water-supplied water systems in the San Francisco Bay Area, THMs will likely persist above health protective benchmarks, but below regulatory standards, if current water treatment practices continue. At least 68% of treatment systems for HTTW samples included carbon-based filters, which should be effective in reducing THM concentrations, and HTTW samples had much lower THM concentrations than TW samples in this study. Given the gap between regulatory standards and health benchmarks for THMs, treatment at home may be the only near-term strategy for mitigation of THMs to health-protective levels. Further THM mitigation in TW is important even if BW is the primary drinking water source for a household, as most people still use TW or HTTW for other domestic purposes and would be exposed to THMs via inhalation [ 79 , 83 ].

3.5 Study limitations

This study addresses several limitations of previous studies, with the inclusion of a large sample size of BW products representative of San Francisco Bay Area consumer choices, an unprecedented number of in-home TW quality results, and “in practice” water quality from people treating their water at home. Still, there are known limitations of this study and areas for future research. First, while data was produced using EPA approved methods, commercial laboratories often have higher detection limits than academic or agency laboratories; several differences in these findings from the recent study on BW by Bradley et al. [ 24 ] indicate differences in analytical sensitivity.

Second, the cumulative toxicity quotient approach assumes that contaminant impacts are cumulative, though some chemicals may be more or less than additive [ 84 ]. The approach is also limited by the analytical scope of the study (conservative with respect to the full range of potential contaminants present) and availability of health benchmarks. For example, various organic contaminants that were not measured here–such as pesticides, PFAS compounds, phthalates and additional DBPs–have been detected in BW in prior studies [ 24 , 28 , 31 , 85 ]. The limitation of scope is also salient in the case of DBPs. There are over 700 known DBPs, many of which are more toxic than THMs, and THMs are not necessarily good surrogates for other DBPs, especially iodine- and nitrogen-containing DBPs that can be formed at higher levels when chloramines are used as disinfectants [ 57 , 86 ]. Thus, it is expected that a broader contaminant panel would indicate further contamination challenges across the three water sources, with unique issues for BW.

The representativeness of the TW and HTTW results is another potential limitation. Samples were taken by individuals in the San Francisco Bay Area but not with explicit representation across water systems, though most water systems had similar water source types and treatment practices. Fig B in S1 File indicates a bias over-representing the five southern counties of the San Francisco Bay Area with respect to the location of samples. The large sample size of results across the nine-county area reflects a range of scenarios, but research into the defining characteristics of people analyzing their tap water would allow for a better characterization of bias in the citizen science data.

Lastly, detailed statistical analyses of source water impacts on toxicity profiles (i.e., surface water versus groundwater versus mixed-sources) were not possible given the available data (see Table F in S1 File ), and future research into this area would support more targeted toxicity mitigation efforts.

4. Conclusions

Alternatives to tap water, including household-scale treatment of tap water and bottled water, are increasing in popularity but information regarding their water quality is limited. This is the first large-scale study comparing the water quality of the realistic consumer drinking water options of bottled water, tap water, and household-treated tap water. Potential aesthetic concerns were identified in all drinking water options, but were more common in TW and HTTW samples, supporting previous evidence that people switch to BW in response to aesthetic concerns. Potential toxicity of samples was also identified despite the quality of the municipally supplied water in the study being largely within state and federal drinking water limits, and the BW quality mostly falling within FDA standards.

Overall, TW had significantly higher average potential toxicity than BW and HTTW. Potential toxicity in all three water sources was primarily attributed to THMs, followed by metals for TW and HTTW, likely derived from distribution systems, household plumbing and/or fixtures, and geogenic elements in groundwater-derived BW and HTTW. Improving THM management across all three water sources would have a significant impact on the cumulative potential toxicity of samples. Average potential toxicity of samples was not significantly different between HTTW and BW, suggesting that BW–which has higher environmental and financial costs than HTTW–is not a superior alternative to TW where household treatment is possible. Persistent aesthetic issues and potential toxicity in HTTW could be addressed by designing household-scale treatment to specifically address identified issues, perhaps in partnership with water systems. This approach is not common and represents an area for future research and policy design to achieve safe water goals. Evidence is provided showing higher water quality among households using household-scale treatment as compared with those using TW, which indicates that treatment at POU can address water quality issues and thus may be a tractable complement to improved TW to improve public health.

Supporting information

https://doi.org/10.1371/journal.pwat.0000272.s001

S1 Text. Methods, ANOVA, and Posthoc tests.

https://doi.org/10.1371/journal.pwat.0000272.s002

Acknowledgments

The bottled water sample collection and analysis was funded by SimpleLab, Inc. We thank Noor Brody for technical review of early versions of the analysis, Alea Laidlaw for research assistance at the project’s inception, and eight anonymous experts for their support on study design. Finally, we thank Carsten Prasse for providing us with critical feedback on the original manuscript.

• 1. Riggs , Hughes J, Irvin D, Leopard K, Riggs E Irvin D, Leopard K HJ. An Overview of Clean Water Access Challenges in the United States. Chapel Hill: US Water Partnership; UNC Environmental Finance Center; 2017. Available: https://www.urbanwaterslearningnetwork.org/wp-content/uploads/2019/05/UNC-Clean-Water-Access-Challenges2017.pdf
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Towards sustainable water use in two university student residences: a case study.

1. Introduction

2. materials and methods, 2.1. location and characteristics of the residences, 2.2. water consumption characterization.

• i : each of the existing devices;
• V : flushing volume (L);
• f : daily frequence of use.
• Q : water flow (L);
• f : daily frequence of use;
• t : duration of each use (minutes).

2.3. Water Use Efficiency Measure Impact

• ρ : water density ( ρ = 1000 kg/m 3 ).
• C p : specific heat of water ( C p = 4187 J/kg × K).
• V : consumption of hot water/resident (L).
• Δ T : Denotes the difference between the cold water inlet temperature and the hot water outlet temperature (°C). According to the long-term climate series [ 40 ], the average annual water temperature in Bragança was estimated at 12.3 °C. The water heating system raised the temperature to 60 °C, resulting in a temperature variation of 47.7 °C.
• η : efficiency of the heating system, which in the present study is 2.97 for both residences.
• V a : volume of rainwater in the reference period (L);
• C : runoff coefficient (dimensionless);
• P : average precipitation accumulated at the site (mm);
• A : catchment area (roof) (m 2 );
• η f : hydraulic filtering efficiency (dimensionless).

3. Results and Discussion

3.1. characterization of water devices and their use patterns, 3.1.1. showers, 3.1.2. flushing cisterns, 3.1.3. urinals, 3.1.4. taps.

• WC basin single-lever taps: These taps had an average flow of 13.29 L/min, and the estimated number of total uses was around three times/day/user; each use is on for approximately 0.18 min (Residence I). In Residence II, these taps presented an average flow of 14 L/min, and the estimated number of total uses was around 3.4 times/day/user; each use was on for approximately 0.23 min. The water category efficiency of these devices is E.
• Timed flow tap: The average flow is 3.63 L/min in both residences. Each use is on for approximately 7.45 s, and it is used 0.33 and 0.38 times/day/user in the male and female residences, respectively. Their water category efficiency is A.
• Kitchen tap: The average flow is 10.6 L/min, and it is used for 6.67 min/day/user (Residence I). In Residence II, the average flow is 9.9 L/min, and it is used for 2.20 min/day/user. Their water category efficiency is C.

3.1.5. Washing Machines

3.1.6. build cleaning, 3.2. water use characterization, 3.3. implementation of water-saving measures, 4. conclusions, author contributions, institutional review board statement, informed consent statement, data availability statement, acknowledgments, conflicts of interest.

• This survey was conducted on all users of Residences I and II, with specific questions addressed to the cleaning staff.
• 2. Age: _________
• 3. How many days a week do you stay at the Residence? ___________
• 4. How often do you wash your hands at the Residence?
• 4.1. How many times do you usually press the push button of the tap? (in the case of the timer taps) _______
• 4.2. How long does the tap remain open while you use the single lever taps? _______
• How often do you use the toilet at the Residence? _______
• 5.1. Indicate the number of flushes each time you use the toilet: _______
• 5.2. What “button” do you usually flush when you use the toilet?
• - The larger “button” (6 L) ⎕
• - The smaller “button” (3 L) ⎕
• - Both “buttons” at the same time ⎕
• - The single “button” (if there is only one “button”) ⎕
• 6. Please estimate the number of times you shower each week: _______________
• 6.1. Give an estimate, in minutes, of the time it takes to shower: _______________
• 7. Do you usually use the washing machine at the Residence?
• 7.1. If you answered “Yes”, please estimate the number of times you use the washing machine each week: _______________ and which washing programs you use ____________________________________________________________.
• 8. Do you usually use the kitchen tap at the Residence?
• 8.1. If you answered “Yes,” please estimate the amount of time, in minutes, that you use the tap each day: _______________
• 9. Do you cook your lunch and/or dinner while you are at the Residence?
• 9.1. If “Yes”, how often do you cook? _______________
• 9.2. If “Yes”, is the stove gas or electric? _____________
• 10. Have you ever detected a leak in the residence water networks?
• 10.1. If “Yes,” please describe what happened. ________________________________________
• 1. How many times a day is the floor washed? ___________
• 2. How is the residence floor washed?
• 2.1. With a mop? _______ How many times a day? _______
• 2.2. What is the capacity of the bucket? _______
• 2.3. How many times do you fill the bucket? _______

• Vörösmarty, C.J.; McIntyre, P.B.; Gessner, M.O.; Dudgeon, D.; Prusevich, A.; Green, P.; Glidden, S.; Bunn, S.E.; Sullivan, C.A.; Liermann, C.R.; et al. Global Threats to Human Water Security and River Biodiversity. Nature 2010 , 467 , 555–561. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Ma, T.; Sun, S.; Fu, G.; Hall, J.W.; Ni, Y.; He, L.; Yi, J.; Zhao, N.; Du, Y.; Pei, T.; et al. Pollution Exacerbates China’s Water Scarcity and Its Regional Inequality. Nat. Commun. 2020 , 11 , 650. [ Google Scholar ] [ CrossRef ]
• Kilinc, E.A.; Tanik, A.; Hanedar, A.; Gorgun, E. Climate Change Adaptation Exertions on the Use of Alternative Water Resources in Antalya, Türkiye. Front. Environ. Sci. 2023 , 10 , 1080092. [ Google Scholar ] [ CrossRef ]
• Water Scarcity Conditions in Europe (Water Exploitation Index Plus). Available online: https://www.eea.europa.eu/en/analysis/indicators/use-of-freshwater-resources-in-europe-1 (accessed on 19 June 2024).
• Spinoni, J.; Vogt, J.V.; Naumann, G.; Barbosa, P.; Dosio, A. Will Drought Events Become More Frequent and Severe in Europe? Int. J. Climatol. 2018 , 38 , 1718–1736. [ Google Scholar ] [ CrossRef ]
• Alvarez, I.; Pereira, H.; Lorenzo, M.N.; Picado, A.; Sousa, M.C.; Taboada, J.J.; Dias, J.M. Drought Projections for the NW Iberian Peninsula under Climate Change. In Climate Dynamics ; Springer: Berlin/Heidelberg, Germany, 2024. [ Google Scholar ] [ CrossRef ]
• Veloso, S.; Tam, C.; Oliveira, T. Effects of Extreme Drought and Water Scarcity on Consumer Behaviour—The Impact of Water Consumption Awareness and Consumers’ Choices. J. Hydrol. 2024 , 639 , 131574. [ Google Scholar ] [ CrossRef ]
• ERSAR—Dados de Base. Available online: https://www.ersar.pt/pt/setor/factos-e-numeros/dados-de-base (accessed on 24 June 2024).
• Naserisafavi, N.; Yaghoubi, E.; Sharma, A.K. Alternative Water Supply Systems to Achieve the Net Zero Water Use Goal in High-Density Mixed-Use Buildings. Sustain. Cities Soc. 2022 , 76 , 103414. [ Google Scholar ] [ CrossRef ]
• Meireles, I.; Sousa, V. Assessing Water, Energy and Emissions Reduction from Water Conservation Measures in Buildings: A Methodological Approach. Environ. Sci. Pollut. Res. 2020 , 27 , 4612–4629. [ Google Scholar ] [ CrossRef ]
• Mannan, M.; Al-Ghamdi, S.G. Environmental Impact of Water-Use in Buildings: Latest Developments from a Life-Cycle Assessment Perspective. J. Environ. Manag. 2020 , 261 , 110198. [ Google Scholar ] [ CrossRef ]
• Rodrigues, F.; Silva-Afonso, A.; Pinto, A.; Macedo, J.; Santos, A.S.; Pimentel-Rodrigues, C. Increasing Water and Energy Efficiency in University Buildings: A Case Study. Environ. Sci. Pollut. Res. 2020 , 27 , 4571–4581. [ Google Scholar ] [ CrossRef ]
• Bonnet, J.-F.; Devel, C.; Faucher, P.; Roturier, J. Analysis of Electricity and Water End-Uses in University Campuses: Case-Study of the University of Bordeaux in the Framework of the Ecocampus European Collaboration. J. Clean. Prod. 2002 , 10 , 13–24. [ Google Scholar ] [ CrossRef ]
• Da Silva, S.F.; Britto, V.; Azevedo, C.; Kiperstok, A. Rational Consumption of Water in Administrative Public Buildings: The Experience of the Bahia Administrative Center, Brazil. Water 2014 , 6 , 2552–2574. [ Google Scholar ] [ CrossRef ]
• Morote, Á.-F.; Hernández, M.; Olcina, J.; Rico, A.-M. Water Consumption and Management in Schools in the City of Alicante (Southern Spain) (2000–2017): Free Water Helps Promote Saving Water? Water 2020 , 12 , 1052. [ Google Scholar ] [ CrossRef ]
• Oduro-Kwarteng, S.; Nyarko, K.B.; Odai, S.N.; Aboagye-Sarfo, P. Water Conservation Potential in Educational Institutions in Developing Countries: Case Study of a University Campus in Ghana. Urban Water J. 2009 , 6 , 449–455. [ Google Scholar ] [ CrossRef ]
• Soares, A.E.P.; Silva, J.K.D.; Nunes, L.G.C.F.; Rios Ribeiro, M.M.; Silva, S.R.D. Water Conservation Potential within Higher Education Institutions: Lessons from a Brazilian University. Urban Water J. 2023 , 20 , 1429–1437. [ Google Scholar ] [ CrossRef ]
• Alghamdi, A.; Haider, H.; Hewage, K.; Sadiq, R. Inter-University Sustainability Benchmarking for Canadian Higher Education Institutions: Water, Energy, and Carbon Flows for Technical-Level Decision-Making. Sustainability 2019 , 11 , 2599. [ Google Scholar ] [ CrossRef ]
• Almeida, A.P.; Sousa, V.; Silva, C.M. Methodology for Estimating Energy and Water Consumption Patterns in University Buildings: Case Study, Federal University of Roraima (UFRR). Heliyon 2021 , 7 , e08642. [ Google Scholar ] [ CrossRef ] [ PubMed ]
• Ruiz-Garzón, F.; del Carmen Olmos-Gómez, M.; Estrada-Vidal, L.I. Perceptions of Teachers in Training on Water Issues and Their Relationship to the SDGs. Sustainability 2021 , 13 , 5043. [ Google Scholar ] [ CrossRef ]
• Marinho, M.; do Socorro Gonçalves, M.; Kiperstok, A. Water Conservation as a Tool to Support Sustainable Practices in a Brazilian Public University. J. Clean. Prod. 2014 , 62 , 98–106. [ Google Scholar ] [ CrossRef ]
• Silva-Afonso, A.; Pimentel-Rodrigues, C.; Meireles, I.; Sousa, V. Feasibility Study of Water Saving Measures in Higher Education Buildings: A Case Study of the University of Aveiro. BJECC 2016 , 6 , 116–127. [ Google Scholar ] [ CrossRef ]
• da Silva, L.C.C.; Filho, D.O.; Silva, I.R.; e Pinto, A.C.V.; Vaz, P.N. Water Sustainability Potential in a University Building—Case Study. Sustain. Cities Soc. 2019 , 47 , 101489. [ Google Scholar ] [ CrossRef ]
• Nunes, L.G.C.F.; Soares, A.E.P.; de Albuquerque Soares, W.; da Silva, S.R. Water Consumption in Public Schools: A Case Study. J. Water Sanit. Hyg. Dev. 2019 , 9 , 119–128. [ Google Scholar ] [ CrossRef ]
• Ragazzi, M.; Ghidini, F. Environmental Sustainability of Universities: Critical Analysis of a Green Ranking. Energy Procedia 2017 , 119 , 111–120. [ Google Scholar ] [ CrossRef ]
• Fidar, A.; Memon, F.A.; Butler, D. Environmental Implications of Water Efficient Microcomponents in Residential Buildings. Sci. Total Environ. 2010 , 408 , 5828–5835. [ Google Scholar ] [ CrossRef ]
• Sharma, A.K. Rainwater Tank Systems for Urban Water Supply: Design, Yield, Energy, Health Risks, Economics and Social Perceptions ; IWA Publishing: London, UK, 2015; Volume 14. [ Google Scholar ] [ CrossRef ]
• Teston, A.; Piccinini Scolaro, T.; Kuntz Maykot, J.; Ghisi, E. Comprehensive Environmental Assessment of Rainwater Harvesting Systems: A Literature Review. Water 2022 , 14 , 2716. [ Google Scholar ] [ CrossRef ]
• Pimentel-Rodrigues, C.; Silva-Afonso, A. Rainwater Harvesting for Irrigation of Tennis Courts: A Case Study. Water 2022 , 14 , 752. [ Google Scholar ] [ CrossRef ]
• Alborzfard, N.; Berardi, U. (Un) Sustainable Water Practices in Dormitories. SB13 Dubai Paper-066. 8 December 2013. Available online: https://www.researchgate.net/profile/Nakisa-Alborz/publication/337438894_Un_Sustainable_Water_Practices_in_Dormitories/links/5dd75bb392851c1feda58494/Un-Sustainable-Water-Practices-in-Dormitories.pdf (accessed on 24 June 2024).
• Bongungu, J.L.; Francisco, P.W.; Gloss, S.L.; Stillwell, A.S. Estimating Residential Hot Water Consumption from Smart Electricity Meter Data. Environ. Res. Infrastruct. Sustain. 2022 , 2 , 045003. [ Google Scholar ] [ CrossRef ]
• Daud, F.M.; Abdullah, S. Water Consumption Trend among Students in a University’s Residential Hall. Malays. J. Soc. Sci. Humanit. (MJSSH) 2020 , 5 , 56–62. [ Google Scholar ] [ CrossRef ]
• De Jonge, L.; De Backer, L.; Van Kenhove, E. Water Use in Collective Student Housing. In Proceedings of the WDSA CCWI 2022: 2nd International Joint Conference on Water Distribution Systems Analysis & Computing and Control in the Water Industry, Proceedings, Valencia, Spain, 18–22 July 2022. [ Google Scholar ]
• Censos 2021-População Residente em Bragança. Available online: https://censos.ine.pt/xportal/xmain?xpgid=censos21_populacao&xpid=CENSOS21 (accessed on 24 June 2024).
• IPMA-Séries Longas. Available online: https://www.ipma.pt/pt/oclima/series.longas/?loc=Bragan%C3%A7a&type=raw (accessed on 24 June 2024).
• Silva-Afonso, A.; Pimentel-Rodrigues, C. The Portuguese System of Certifying and Labeling Water-Efficiency Products. J. Am. Water Work. Assoc. 2010 , 102 , 52–56. [ Google Scholar ] [ CrossRef ]
• Faia, V. Metodologia de cálculo de Consumos para Classificação de Eficiência Hídrica nos Edifícios Residenciais. Master’s Thesis, Universidade de Lisboa-Instituto Superior Técnico, Lisboa, Portugal, 2021. (In Portuguese). [ Google Scholar ]
• Faia, V.; Poças, A.; Silva, C.; Newton, F.; Malta Dias, P. Eficiência hídrica e nexus água-energia: Modelo Quantitativo de impacto de medidas de melhoria nos edifícios residenciais. In Proceedings of the XX SILUBESA-Simpósio Luso-Brasileiro de Engenharia Sanitária e Ambiental, Aveiro, Portugal, 29 June–1 July 2022. [ Google Scholar ]
• Vermeulen, H.J.; Fast, S. Electrical Energy Consumption Analysis for Sanitary Water Heating in Student Residences. In Proceedings of the 2016 International Conference on the Domestic Use of Energy (DUE), Cape Town, South Africa, 29–31 March 2016; pp. 1–6. [ Google Scholar ]
• IPMA-Clima Normais. Available online: https://www.ipma.pt/pt/oclima/normais.clima/ (accessed on 19 June 2024).
• Sousa, V.; Silva, C.M.; Meireles, I.C. Technical-Financial Evaluation of Rainwater Harvesting Systems in Commercial Buildings–Case Ase Studies from Sonae Sierra in Portugal and Brazil. Environ. Sci. Pollut. Res. 2018 , 25 , 19283–19297. [ Google Scholar ] [ CrossRef ]
• Technical Commitee 0701. Available online: https://www.anqip.com/storage/2024/04/03/34/e3045579.pdf (accessed on 19 June 2024).
• Santos, C.; Taveira-Pinto, F. Analysis of Different Criteria to Size Rainwater Storage Tanks Using Detailed Methods. Resour. Conserv. Recycl. 2013 , 71 , 1–6. [ Google Scholar ] [ CrossRef ]
• Balado-Naves, R.; Suárez-Fernández, S. Exploring Gender Differences in Residential Water Demand. Water Resour. Econ. 2024 , 46 , 100243. [ Google Scholar ] [ CrossRef ]
• Granda, L.; Moya-Fernández, P.J.; Soriano-Miras, R.M.; González-Gómez, F. Pro-Environmental Behaviour in Household Water Use. A Gender Perspective. Sustain. Water Resour. Manag. 2024 , 10 , 49. [ Google Scholar ] [ CrossRef ]
• Ibáñez-Rueda, N.; Guardiola, J.; López-Ruiz, S.; González-Gómez, F. Towards a Sustainable Use of Shower Water: Habits and Explanatory Factors in Southern Spain. Sustain. Water Resour. Manag. 2023 , 9 , 121. [ Google Scholar ] [ CrossRef ]
• de Sá Silva, A.C.R.; Bimbato, A.M.; Balestieri, J.A.P.; Vilanova, M.R.N. Exploring Environmental, Economic and Social Aspects of Rainwater Harvesting Systems: A Review. Sustain. Cities Soc. 2022 , 76 , 103475. [ Google Scholar ] [ CrossRef ]
• Fator de Emissão da Eletricidade-2023 Agência Portuguesa do Ambiente. Available online: https://www.apambiente.pt/sites/default/files/_Clima/Inventarios/20230427/FE_GEE_Eletricidade2023rev3.pdf (accessed on 19 June 2024).
• Pereira, S.C.; Marta-Almeida, M.; Carvalho, A.C.; Rocha, A. Extreme precipitation events under climate change in the Iberian Peninsula. Int. J. Climatol. 2020 , 40 , 1255–1278. [ Google Scholar ] [ CrossRef ]
• Água Para Reutilização (ApR)|Agência Portuguesa Do Ambiente. Available online: https://apambiente.pt/agua/agua-para-reutilizacao-apr (accessed on 13 August 2024).
• Antão-Geraldes, A.M.; Pinto, M.; Afonso, M.J.; Albuquerque, A.; Calheiros, C.S.C.; Silva, F. Promoting Water Efficiency in a Municipal Market Building: A Case Study. Hydrology 2023 , 10 , 69. [ Google Scholar ] [ CrossRef ]
• Grafton, R.Q.; Manero, A.; Chu, L.; Wyrwoll, P. The Price and Value of Water: An Economic Review. Camb. Prism. Water 2023 , 1 , e3. [ Google Scholar ] [ CrossRef ]
• Morales-Pinzón, T.; Lurueña, R.; Rieradevall, J.; Gasol, C.M.; Gabarrell, X. Financial Feasibility and Environmental Analysis of Potential Rainwater Harvesting Systems: A Case Study in Spain. Resour. Conserv. Recycl. 2012 , 69 , 130–140. [ Google Scholar ] [ CrossRef ]
• Morales-Pinzón, T.; Rieradevall, J.; Gasol, C.M.; Gabarrell, X. Modelling for Economic Cost and Environmental Analysis of Rainwater Harvesting Systems. J. Clean. Prod. 2015 , 87 , 613–626. [ Google Scholar ] [ CrossRef ]
• Silva, F.; Barros, J.; Afonso, M.J.A.P.S.; de Oliveira, G.G.L.; Fachada, I.; Antão-Geraldes, A.M. Promoting Water Efficiency in a Student Residence as a Contribution to Sustainability: hydroSAAP Innovation Project. In Proceedings of the INTED2024 Proceedings—18th International Technology, Education and Development Conference, Valencia, Spain, 4–6 March 2024; pp. 2153–2162. [ Google Scholar ] [ CrossRef ]

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Antão-Geraldes, A.M.; Ohara, G.; Afonso, M.J.; Albuquerque, A.; Silva, F. Towards Sustainable Water Use in Two University Student Residences: A Case Study. Appl. Sci. 2024 , 14 , 7559. https://doi.org/10.3390/app14177559

Antão-Geraldes AM, Ohara G, Afonso MJ, Albuquerque A, Silva F. Towards Sustainable Water Use in Two University Student Residences: A Case Study. Applied Sciences . 2024; 14(17):7559. https://doi.org/10.3390/app14177559

Antão-Geraldes, Ana M., Gabriel Ohara, Maria João Afonso, Antonio Albuquerque, and Flora Silva. 2024. "Towards Sustainable Water Use in Two University Student Residences: A Case Study" Applied Sciences 14, no. 17: 7559. https://doi.org/10.3390/app14177559

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