Drinking water quality in the United States

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Drinking water quality in the United States is generally good. In 2006, 89.3 percent of the nation's community water systems were in compliance with all more-than-90 U.S. Environmental Protection Agency (EPA) standards.[1]:220 Most of the systems out of compliance are small systems in rural areas and small towns, partly because most public water systems are small ones. Drinking water quality in the U.S. is regulated by state and federal laws and codes, which set Maximum Contaminant Levels for some pollutants and naturally occurring constituents, determine various operational requirements, require public notification for violation of standards, provide guidance to state primacy agencies, and require utilities to publish consumer confidence reports.


Historically, up through 1914, drinking water quality in the country was managed at the state and local level. After that, interstate waters were protected using United States Public Health Service (USPHS) standards. Ultimately the USPHS standards were adopted and expanded as national drinking water standards after passage of the 1974 Safe Drinking Water Act, and U.S. water quality became subject to a whole new generation of federal standards.[2]

Enforcement of standards[edit]

The Safe Drinking Water Act (SDWA) requires EPA to issue federal regulations for public water systems.[3][4] There are no federal regulations covering private drinking water wells, although some state and local governments have issued rules for these wells.[5] The EPA enters into primary enforcement authority (primacy) agreements with state governments, so in most states the EPA does not directly enforce the SDWA. State rules can be different from the EPA's, but they must be at least as stringent.[6]

The EPA defines a public water system (PWS) as an entity that provides water for human consumption to at least 25 people (or at least 15 connections) for at least 60 days a year. There are three types of public water system: community systems (like cities or trailer parks); non-transient, non-community systems (like factories or schools with their own water source); and transient non-community systems (like rural restaurants or camps).[7]

Enforcement of drinking water standards in small water systems is less consistent than enforcement in large systems. According to a USA Today article published in March 2016, more than 3/4ths of small community water systems classified as having serious health violations by the EPA still have the same violations three years later. Some violations included an overabundance of lead, exceeding allowed rates for nitrate and fecal coliform. Around half of the most contaminated water systems were located in Kansas, Texas and Puerto Rico. In a letter, the EPA’s Office of Enforcement and Compliance Assurance noted that the EPA faced “a daunting list of challenges” in its continuing efforts, particularly with small systems that “lack the basic infrastructure, resources and capacity to provide clean drinking water.” [8]

Consumer Confidence Reports[edit]

EPA's Consumer Confidence Rule of 1998 requires community public water suppliers to provide customers with annual reports of drinking water quality, called Consumer Confidence Reports (CCR).[9] Each year by July 1 anyone connected to a public water system should receive in the mail an annual water quality report that tells where your water comes from and what's in it. Consumers can find out about these local reports on a map provided by EPA.[10] According to the science writer Elizabeth Royte these reports, written by utilities, "can be flawed, and some are essentially propaganda. They report yearly averages over time and, with some contaminants, over multiple locations within a system, which can obscure spikes." In addition, they don't necessarily list contaminants that aren't regulated and say nothing about contamination that may occur within the plumbing system of a building.[1]:223 A study of the 2001 water quality reports of 19 cities published by the Natural Resources Defense Council gave two of them--Newark and Phoenix—a failing grade for "burying, obscuring and omitting findings about health effects of contaminants in city water supplies and printing misleading statements." Even the cities to which the study assigned grades of "Good" and "Fair" included some false claims, errors and misleading data.[11][12]

Substances for which there are federal standards[edit]

Federal drinking water standards are organized into six groups:

  • Microorganisms
  • Disinfectants
  • Disinfection byproducts
  • Inorganic chemicals
  • Organic chemicals
  • Radionuclides.[13]


EPA has issued standards for Cryptosporidium, Giardia lamblia, Legionella, coliform bacteria and enteric viruses. EPA also requires two microorganism-related tests to indicate water quality: plate count and turbidity.[13]


Cryptosporidium is a parasite that has a thick outer shell and thus is highly resistant to disinfection with chlorine. It gets into rivers and lakes from the stools of infected animals. Municipal water treatment plants usually remove Cryptosporidium oocysts through filtration. Nevertheless, at least five outbreaks of cryptosporidiosis in the U.S. have been associated with contaminated drinking water, including a well-publicized one in Milwaukee, Wisconsin in 1993.

The Long Term 2 Enhanced Surface Water Treatment Rule ("LT2 rule") of 2006 requires evaluation of surface water treatment plants and specific treatments be provided in order to minimize the potential for Cryptosporidium infections from public water at supplies using surface water.[14]


EPA has issued standards for chlorine, chloramine and chlorine dioxide.[13]

Disinfection by-products[edit]

EPA has issued standards for bromate, chlorite, haloacetic acids and trihalomethanes.[13]

Disinfectants such as chlorine can react with natural material in the water to form disinfection byproducts such as trihalomethanes. Animal studies indicate that none of the chlorination byproducts studied to date is a potent carcinogen at concentrations normally found in drinking water. According to the "GreenFacts" website, there is insufficient epidemiological evidence to conclude that drinking chlorinated water causes cancers. The results of currently published studies do not provide convincing evidence that chlorinated water causes adverse pregnancy outcomes.[15]

Inorganic chemicals[edit]

EPA has issued standards for antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, copper, cyanide, fluoride, lead, mercury, nitrate, nitrite, selenium and thallium.[13]


Arsenic occurs naturally in water or enters it through pollution. If a person drinks two liters (more than half a gallon) of tap water that exceeds the former Maximum Contaminant Level of 50 parts per billion (ppb) every day over a lifetime, there is a risk of cancer. EPA reduced this level to 10 parts per billion (ppb) in 2001 and drinking water systems had to comply with the new regulation starting in 2006.[16][17] A 2017 Lancet Public Health study found that this rule change led to fewer cancer deaths.[18][19]

The National Research Council estimates that men and women who daily consume water containing 20 ppb of arsenic have about a 0.7% increased risk of developing bladder or lung cancer during their lifetime.[20] According to a 2009 film, millions of private wells have unknown arsenic levels, and in some areas of the US, over 20 percent of wells may contain levels that are not safe.[21]


Most people associate fluoride with the practice of intentionally adding fluoride to public drinking-water supplies for the prevention of tooth decay. However, fluoride can also enter public water systems from natural sources, including runoff from weathering of fluoride-containing rocks and soils and leaching from soil into groundwater. Fluoride pollution from various industrial emissions can also contaminate water supplies. In a few areas of the United States, fluoride concentrations in water are much higher than normal, mostly from natural sources. In 1986, EPA established a maximum allowable concentration for fluoride in drinking water of 4 milligrams per liter (mg/L). After reviewing research on various health effects from exposure to fluoride, the Committee on Fluoride in Drinking Water of the National Research Council concluded in 2006 that EPA's drinking water standard for fluoride does not protect against adverse health effects. Just over 200,000 Americans live in communities where fluoride levels in drinking water are 4 mg/L or higher. Children in those communities are at risk of developing severe tooth enamel fluorosis, a condition that can cause tooth enamel loss and pitting. It can also increase the risk of bone fractures. The report concluded unanimously that the present maximum contaminant level goal of 4 mg/L for fluoride should be lowered.[20]

Several states have more stringent regulations.[citation needed]


Lead typically gets into drinking water after the water leaves the treatment plant. The source of lead is most likely pipe or solder in older service connections or older plumbing inside homes, from which lead "leaks" into the water through corrosion. EPA's lead and copper rule set an "action level" of 15 parts per billion (ppb), which is different from a Maximum Contaminant Level.[22]

If tests show that the level of lead drinking water is in the area of 15 ppb or higher, it is advisable – especially if there are young children in the home – to replace old pipes, to filter water, or to use bottled water. EPA estimates that more than 40 million U.S. residents use water "that can contain lead in excess of 15 ppb".[23] In Washington, DC these concerns have led to a $408 million program carried out since 2004 to replace lead service connections to about 35,000 homes. The effectiveness of the program has, however, been put in question in 2008 by WASA, the city's utility.[24] In 2016, more than 5,000 drinking water systems were found to be in violation of the EPA's lead and copper rule.[25]

Organic chemicals[edit]

EPA has issued standards for 53 organic compounds, including benzene, dioxin (2,3,7,8-TCDD), PCBs, styrene, toluene, vinyl chloride and several pesticides.[13]


EPA has issued standards for alpha particles, beta particles and photon emitters, radium and uranium.[13]

Substances for which there are no federal standards[edit]

EPA maintains a list of substances which are proposed for regulation in drinking water.[26] In an effort to assess the importance of certain substances as contaminants, the National Primary Drinking Water Regulations have required some public water systems to monitor for some of those substances.[27]


Methyl tert-butyl ether is regulated by some states, including California and New York.


Perchlorate has been detected in public drinking water supplies of over 11 million people in 22 states at concentrations of at least 4 parts per billion (ppb).[28] Above a certain concentration perchlorate alters the production of thyroid hormones by the body, chemicals that are essential for proper development of the fetus and for normal metabolic functioning of the body. According to patient advocate and writer Mary Shomon, people with thyroid conditions, as well as pregnant women and their fetuses are particularly at risk.[29] However, according to the Perchlorate Information Bureau, an industry-supported group, sound scientific and medical research shows that the low levels of perchlorate being detected in drinking water are not dangerous to human health. Still according to the same source, these studies on adults, newborns and children provide reason to believe that low levels of perchlorate (even at levels many times higher than the minute amounts being found in some drinking water supplies) also have no measurable effect on pregnant women or fetuses.[30]

One source of perchlorate in drinking water is the past production of solid rocket propellants using perchlorate, combined with poor disposal practices. Industrial accidents and agricultural fertilizers are also suspected as sources of contamination of drinking water by perchlorate. Perchlorate is also found in breast milk at significant levels, possibly attributable to perchlorate in drinking water and foods.[31] The challenge of defining an acceptable level of perchlorate in drinking water sets two opposing groups with significantly different views against each other. In a draft risk assessment made in 2002, EPA suggested that levels higher than 1 part per billion (ppb) pose a health risk. In contrast, the Defense Department contended that perchlorate at 200 ppb has no lasting effect on humans. Perchlorate is one of only four of the seventy chemicals for which EPA has set public health goals that have a safety factor of 10, rather than the usual safety factors of 100 or 1000.[29][32]:21 In 2004 eight states had non-binding advisories for perchlorate in drinking water, ranging from 1 to 18 ppb. Only two states—Massachusetts and California—set legally binding maximum contaminant levels on the allowable amount of perchlorate in drinking water, at 2 ppb and 6 ppb respectively.[31][33]

EPA issued an "Interim Health Advisory" for perchlorate in 2009, while it continued to evaluate whether to issue regulatory standards.[32] In 2011 the agency announced that it would develop regulations for perchlorate.[34][35] In 2016 a federal district court in New York issued a consent decree requiring EPA to issue a proposed rule for perchlorate in October 2018, and a final rule in December 2019.[36]

Pharmaceutical substances[edit]

Many pharmaceutical substances are not regulated under the Safe Drinking Water Act. They have been found in tiny concentrations in the drinking water of several US cities affecting at least 41 million Americans, according to a five-month inquiry by the Associated Press published in March 2008. According to the AP report, researchers do not yet understand the exact risks from decades of persistent exposure to random combinations of low levels of pharmaceuticals.[37]

Pharmaceuticals are included in a broader group of substances currently being studied by EPA, "Pharmaceuticals and Personal Care Products (PPCPs)." This group includes classes of common consumer products such as cosmetics, fragrances, vitamins and sunscreen products.[38]


EPA proposed regulations for radon in 1991 and 1999.[39] In 2010 it was reported that EPA had not finalized the proposal due to concerns raised by some utilities about high costs for controlling radon. However, nine states had issued their own radon guidelines.[40]

See also[edit]


  1. ^ a b Royte, Elizabeth (2008). Bottlemania: How Water Went on Sale and Why We Bought It. New York: Bloomsbury USA. ISBN 159691372X. 
  2. ^ EPA Alumni Association: Senior EPA officials discuss early implementation of the Safe Drinking Water Act of 1974, Video, Transcript. (see p3)
  3. ^ United States. Safe Drinking Water Act. Pub.L. 93–523; 88 Stat. 1660; 42 U.S.C. § 300f et seq. 1974-12-16.
  4. ^ "Safe Drinking Water Act". Washington, D.C.: U.S. Environmental Protection Agency (EPA). 2016-09-27. 
  5. ^ "About Private Water Wells". EPA. 2015-11-17. 
  6. ^ Understanding the Safe Drinking Water Act (Report). EPA. June 2004. EPA 816-F-04-030. 
  7. ^ "Background on Drinking Water Standards in the Safe Drinking Water Act". EPA. 2015-12-23. 
  8. ^ https://www.usatoday.com/story/news/nation/2016/03/22/lead-in-drinking-water-epa-report/82128166/
  9. ^ "Consumer Confidence Reports". EPA. 2016-10-26. 
  10. ^ "Find Your Local CCR". Consumer Confidence Reports. EPA. Retrieved 2016-10-26. 
  11. ^ Natural Resources Defense Council (NRDC), New York, NY (2003). "What's on Tap? Grading Drinking Water in U.S. Cities." Chapter 3: "Right-to-know reports."
  12. ^ "A Guide to Understanding Your CCR". Drinking Water. Atlanta, GA: U.S. Centers for Disease Control. 2015. 
  13. ^ a b c d e f g "National Primary Drinking Water Regulations". EPA. 2017-07-11. 
  14. ^ "Long Term 2 Enhanced Surface Water Treatment Rule Documents". Drinking Water Requirements for States and Public Water Systems. EPA. 2016-11-02. 
  15. ^ "Scientific Facts on Water Disinfectants & disinfectant by-products summary by GreenFacts of the ICPS Environmental Health Criteria 216". Brussels, Belgium: GreenFacts. Retrieved 2008-08-27. 
  16. ^ "Chemical Contaminant Rules". Drinking Water Requirements for States and Public Water Systems. EPA. 2017-04-24. 
  17. ^ NRDC (2009). "Arsenic in Drinking Water."
  18. ^ Bakalar, Nicholas (2017-10-24). "Arsenic Reductions in Drinking Water Tied to Fewer Cancer Deaths". The New York Times. ISSN 0362-4331. Retrieved 2017-10-26. 
  19. ^ Nigra, Anne E.; Sanchez, Tiffany R.; Nachman, Keeve E.; Harvey, David E.; Chillrud, Steven N.; Graziano, Joseph H.; Navas-Acien, Ana (2017-10-22). "The effect of the Environmental Protection Agency maximum contaminant level on arsenic exposure in the USA from 2003 to 2014: an analysis of the National Health and Nutrition Examination Survey (NHANES)". The Lancet Public Health. 0 (0). doi:10.1016/S2468-2667(17)30195-0. ISSN 2468-2667. 
  20. ^ a b National Academy of Sciences, Washington, DC. "Drinking Water Quality and Contamination." National Academies' Water Information Center.[dead link]
  21. ^ Dartmouth Medical School. Dartmouth Toxic Metals Superfund Research Program. Hanover, NH (2009). "In Small Doses." Video.
  22. ^ Lead and Copper Rule: A Revised Quick Reference Guide (Report). EPA. 2008. EPA 816-F-08-018. 
  23. ^ Lead in Your Drinking Water; Actions You Take To Reduce Lead In Drinking Water (Report). EPA. June 1993. EPA 810-F-93-001. 
  24. ^ Duggan, Paul (2008-01-26). "Doubts on Lead Pipe Replacement". Washington Post. 
  25. ^ Ganim, Sara (2016-06-29). "5,300 U.S. water systems are in violation of lead rules". cnn.com. 
  26. ^ EPA (2011). "Basic Information on Contaminant Candidate List and Regulatory Determinations"
  27. ^ EPA. "National Primary Drinking Water Regulations: Monitoring requirements for unregulated contaminants." Code of Federal Regulations, 40 C.F.R. 141.40. Revised 2007.
  28. ^ Health Implications of Perchlorate Ingestion. Washington, D.C.: National Research Council. 2005. doi:10.17226/11202. ISBN 0-309-09568-9.  Committee to Assess the Health Implications of Perchlorate Ingestion.
  29. ^ a b Shomon, Mary (2016-02-20). "Suspect Salads: Lettuce May Be Toxic To Your Thyroid! Toxic Rocket Fuel Found in Samples of Winter Lettuce". VeryWell. New York: About, Inc. 
  30. ^ Perchlorate Information Bureau, Sacramento, CA. "The Facts About Perchlorate."
  31. ^ a b "Perchlorate Information". Boston, MA: Massachusetts Department of Environmental Protection. Retrieved 2017-04-26. 
  32. ^ a b Interim Drinking Water Health Advisory for Perchlorate (Report). EPA. December 2008. EPA 822-R-08-25. 
  33. ^ "Perchlorate in Drinking Water". Sacramento, CA: California State Water Resources Control Board. 2016-02-22. 
  34. ^ "Perchlorate in Drinking Water". Drinking Water Contaminants—Standards and Regulations. EPA. 2017-03-31. 
  35. ^ EPA (2011-02-11). "Drinking Water: Regulatory Determination on Perchlorate." Federal Register, 76 FR 7762
  36. ^ Natural Resources Defense Council, Inc. v. United States Environmental Protection Agency and Gina McCarthy, 16 Civ. 1251 (ER). United States District Court for the Southern District of New York. Consent Decree filed October 17, 2016.
  37. ^ "AP Probe Finds Drugs in Drinking Water" by Jeff Donn, Martha Mendoza, and Justin Pritchard, Associated Press, March 9, 2008 Archived April 4, 2008, at the Wayback Machine.
  38. ^ "Pharmaceuticals and Personal Care Products". EPA. 2010. Archived from the original on 2015-09-05. 
  39. ^ "Proposed Radon in Drinking Water Regulation". EPA. 2014-06-14. 
  40. ^ Vaidyanathan, Gayathri (2010-12-07). "States Pursue Radon Limits in Drinking Water as EPA Action Lags". New York Times. 

Further reading[edit]

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