Since the Safe Drinking Water Act was passed in 1974, the U.S. Environmental Protection Agency has regulated a growing list of contaminants to protect public drinking water. The SDWA requires the more than 170,000 public water systems in the United States to regularly test their water supply against both naturally-occurring and manmade contaminants that may be found in drinking water.
Still, every year dozens of potentially harmful contaminants are found to be in excess of their EPA-set limits. In the last four decades, the EPA has issued more than 15,000 violations for the presence of dangerous levels of chemicals in municipal water supplies around the country.
To determine the counties with the most contaminated water, 24/7 Wall St. reviewed the number of water quality violations the EPA issued to each public water system in the United States and its territories from September 30, 1980 to July 3, 2017 using data from the EPA’s Safe Drinking Water Information System. There are 23 counties that were issued more than 50 water quality violations over that period.