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.

Enforcement of standards[edit]

The Safe Drinking Water Act (SDWA) contains the federal regulations for public water systems.[2] There are no federal regulations for private drinking water.[3] 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.

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).

Enforcement of drinking water standards in small water systems is less consistent than enforcement in large systems. According to a New York Times analysis published in December 2009, more than 20 percent of public water systems in the U.S. providing water to 49 million people violated provisions of the Safe Drinking Water Act over the previous five years. Violations involved arsenic, radioactive substances like uranium, tetrachloroethylene, and coliform bacteria. Fewer than 6 percent of the public water systems that broke the law were ever fined or punished by state or federal officials. According to David Uhlmann, a former Justice Department official, "there is significant reluctance within the EPA and Justice Department to bring actions against municipalities, because there’s a view that they are often cash-strapped, and fines would ultimately be paid by local taxpayers". A longtime EPA enforcement official who was quoted in the report said "The top people want big headlines and million-dollar settlements. That’s not drinking-water cases." State regulators rather provide technical assistance to help systems that violate the rules. But many systems remained out of compliance, even after aid was offered. For over a quarter of systems that violated the arsenic or radioactivity standards, there is even no record that they were ever contacted by a regulator.[4]

Consumer Confidence Reports[edit]

EPA's Consumer Confidence Rule of 1998 requires community public water suppliers to provide Consumer Confidence Reports (CCR), also known as annual reports of drinking water quality, to their customers.[5] 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.[6] According to the science writer Elizabeth Royte these consumer confidence 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.[7][8]

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.[9]

Microorganisms[edit]

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.[9]

Cryptosporidium[edit]

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.[10]

Disinfectants[edit]

EPA has issued standards for chlorine, chloramine and chlorine dioxide.[9]

Disinfection by-products[edit]

EPA has issued standards for bromate, chlorite, haloacetic acids and trihalomethanes.[9]

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 GreenFacts, 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.[11]

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.[9]

Arsenic[edit]

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 2002 and drinking water systems had to comply with the new regulation starting in 2006.[12][13] 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.[14] 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.[15]

Fluoride[edit]

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.[14]

Several states have more stringent regulations.[citation needed]

Lead[edit]

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.

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".[16] 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.[17]

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.[9]

Radionuclides[edit]

EPA has issued standards for alpha particles, beta particles and photon emitters, radium and uranium.[9]

Substances for which there are no federal standards[edit]

EPA maintains a list of substances which are proposed for regulation in drinking water.[18] 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.[19]

MTBE[edit]

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

Perchlorate[edit]

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).[20] 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.[21] 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.[22]

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.[23]

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 70 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.[21][24] In October 2008 EPA refused to set a drinking water safety standard for perchlorate, saying that "in more than 99 percent of public drinking water systems, perchlorate was not at levels of public health concern" using a benchmark of 15 ppb. EPA encouraged states to set their own standards in accordance to local conditions.[25] 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.[23][26]

Environmental organizations have criticized EPA's decision not to set a federal drinking water safety standard for perchlorate. On October 2, 2008, the environmental law firm Earthjustice announced that it would file suit against the Agency.[27]

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.[28]

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.[29]

Radon[edit]

USEPA proposed regulations for radon in 1991 and 1999.[30]

See also[edit]

References[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. ^ Safe Water Drinking Act, US EPA
  3. ^ Drinking Water From Household Wells, US EPA
  4. ^ Duhigg, Charles (2009-12-07). "Millions in U.S. Drink Dirty Water, Records Show". New York Times. 
  5. ^ U.S. Environmental Protection Agency (EPA), Washington, DC (2011). "Consumer Confidence Reports: Basic Information."
  6. ^ EPA (2011). "Where You Live: Your Drinking Water Quality Reports Online."
  7. ^ 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."
  8. ^ U.S. Centers for Disease Control, Atlanta, GA (2010). "Understanding Consumer Confidence Reports."
  9. ^ a b c d e f g EPA (2013). "Drinking Water Contaminants."
  10. ^ EPA (2011). "Long Term 2 Enhanced Surface Water Treatment Rule."
  11. ^ "Scientific Facts on Water Disinfectants & disinfectant by-products summary by GreenFacts of the ICPS Environmental Health Criteria 216". GreenFacts, Brussels, Belgium. Retrieved 2008-08-27. 
  12. ^ EPA (2010). "Basic Information about the Arsenic Rule."
  13. ^ NRDC (2009). "Arsenic in Drinking Water."
  14. ^ a b National Academy of Sciences, Washington, DC. "Drinking Water Quality and Contamination." National Academies' Water Information Center.
  15. ^ Dartmouth Medical School. Dartmouth Toxic Metals Superfund Research Program. Hanover, NH (2009). "In Small Doses." Video.
  16. ^ EPA (2011). "Lead in Drinking Water."
  17. ^ Duggan, Paul (2008-01-26). "Doubts on Lead Pipe Replacement". Washington Post. 
  18. ^ EPA (2011). "Basic Information on Contaminant Candidate List and Regulatory Determinations"
  19. ^ EPA. "National Primary Drinking Water Regulations: Monitoring requirements for unregulated contaminants." Code of Federal Regulations, 40 C.F.R. 141.40. Revised 2007.
  20. ^ National Research Council (2005). "Health Implications of Perchlorate Ingestion." Committee to Assess the Health Implications of Perchlorate Ingestion. ISBN 0-309-09568-9.
  21. ^ a b Perchlorate in Your Drinking Water. How much is too much and who is at risk? From Mary J. Shomon, With Dr. William Cline, for About.com, March 18, 2004
  22. ^ Perchlorate Information Bureau, Sacramento, CA. "The Facts About Perchlorate."
  23. ^ a b Massachusetts Department of Environmental Protection, Boston, MA (2006). "Frequently Asked Questions: Perchlorate."
  24. ^ EPA (2011). "Perchlorate."
  25. ^ EPA Seeks Comment on Preliminary Perchlorate Drinking Water Decision - Agency Plans to Issue a Perchlorate Health Advisory, October 3, 2008
  26. ^ California Department of Public Health:Perchlorate in Drinking Water
  27. ^ Washington Post, EPA makes no rule on chemical in water, October 4, 2008
  28. ^ "AP Probe Finds Drugs in Drinking Water" by Jeff Donn, Martha Mendoza, and Justin Pritchard, Associated Press, March 9, 2008[dead link]
  29. ^ EPA (2010). "Pharmaceuticals and Personal Care Products (PPCPs)."
  30. ^ EPA (2010). "Radon in Drinking Water."

External links[edit]