Drinking water quality in the United States

Drinking water quality in the United States is regulated by the Safe Drinking Water Act (SDWA), which sets Maximum Contaminant Levels for pollutants. In addition, the EPA's Consumer Confidence Rule of 1998 requires most public water suppliers to provide consumer confidence reports (CCR), also known as annual water quality reports, to their customers. ^[1] Each year by July 1st 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.^[2]

Despite the generally good quality of drinking water in the United States, there are several pollutants of concern listed below in alphabetical.

Cryptosporidium 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. There are no federal or state regulatory standards for Cryptosporidium in drinking water because there is not enough information on which to base standards.^[3]

Disinfection by-products Disinfectants such as chlorine can react with natural material in the water to form disinfection by-products such as trihalomethanes. Animal studies indicate that none of the chlorination by-products 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.^[4]

Lead Another issue of concern is lead in drinking water. Typically, lead 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.^[5] 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 qustion in 2008 by WASA, the city's utility.^[6]

Perchlorates Perchlorates have been detected in public drinking water in at least 22 states. 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. Particularly at risk are people with thyroid conditions, as well as pregnant women and their fetuses. 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.^[7]

The challenge of defining an acceptable level of perchlorates in drinking water sets two opposing groups with significantly different views against each other. In a draft risk assessment made in 2002 the 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 the EPA has set public health goals that have a safety factor of 10, rather then the usual safety factors of 100 or 1000. ^{[8] [9]} In October 2008 the 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. The EPA encouraged states to set their own standards in accordance to local conditions. ^[10] 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.^{[11] [12]} Environmental organizations have criticized the EPA decision not to set a federal drinking water safety standard for perchlorates. The environmental law firm Earthjustice announced that it would sue against it.^[13]

Pharmaceutical substances Pharmaceutical substances that are not regulated under the Act are an issue of concern. 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.^[14]

• Drinking water
• Water pollution
• Water quality
• Water supply and sanitation in the United States