Wellness Health & Well-being Tap Water in 42 States Contaminated by Chemicals EWG tap water probe reveals 141 unregulated chemicals flowing into U.S. homes By Larry West Writer University of Washington Larry West is an award-winning environmental journalist and writer. He won the Edward J. Meeman Award for Environmental Reporting. our editorial process Larry West Updated May 25, 2018 Shilpa Harolikar/Moment Open/Getty Images Share Twitter Pinterest Email Wellness Health & Well-being Clean Beauty Public water supplies in 42 U.S. states are contaminated with 141 unregulated chemicals for which the U.S. Environmental Protection Agency has never established safety standards, according to an investigation by the Environmental Working Group (EWG). Tainted Tap Water Used by Millions of Americans Another 119 regulated chemicals—a total of 260 contaminants altogether—were found by the environmental group in a two-and-a-half-year analysis of more than 22 million tap water quality tests. The tests, which are required under the federal Safe Drinking Water Act, were conducted at nearly 40,000 utilities that supply water to 231 million people. Pollution Threatens Tap Water Quality According to a report by the EWG, the top 10 states with the most contaminants in their drinking water were California, Wisconsin, Arizona, Florida, North Carolina, Texas, New York, Nevada, Pennsylvania, and Illinois—in that order. EWG said the biggest sources of contaminants were agriculture, industry, and pollution from sprawl and urban runoff. Utilities Need More Enforceable Standards for Tap Water EWG's analysis also found that almost all U.S. water utilities comply fully with enforceable health standards once they are developed. The problem, according to the environmental group, is the EPA's failure to establish enforceable health standards and monitoring requirements for many tap water contaminants. "Our analysis clearly demonstrates the need for greater protection of the nation's tap water supplies, and for increased health protections from a number of pollutants that are commonly found but currently unregulated." said Jane Houlihan, vice president for science at EWG, in a prepared statement. "Utilities routinely go beyond what is required to protect consumers from these contaminants, but they need more money for testing, and for protection of vital source waters." Additional Information: Why Is Chlorine Added to Tap Water?Does Fluoride in Tap Water Improve or Harm Your Health?