Since 2004, testing by water utilities has found 315 pollutants in the tap water Americans drink, according to an Environmental Working Group drinking water quality analysis.
More than half of the chemicals detected are not subject to health or safety regulations and can legally be present in any amount. Recent studies have found that even some of the chemicals regulated by the 2000 law pose risks at much smaller concentrations than previously known. The federal government has health guidelines for some, but 49 of these contaminants have been found at levels above those guidelines, polluting the tap water for 53.6 million Americans.
Only 91 contaminants are regulated by the Safe Drinking Water Act, yet more than 60,000 chemicals are used within the United States, according to Environmental Protection Agency estimates. Government and independent scientists have identified hundreds of chemicals associated with a risk of cancer and other diseases at small concentrations in drinking water.