Testing Finds Hundreds of Contaminants in America’s Drinking Water
The Environmental Working Group's analysis of nearly 20 million drinking water tests conducted by water suppliers nationwide between 2004 and 2009 revealed hundreds of pollutants in U.S. tap water. For most, the government has set no safety-based legal limits. Many other contaminants were found in drinking water at concentrations above government-issued advisory health guidelines.
EWG obtained this test data from state water authorities over the past three years, compiling it into the largest database of tap water quality in existence. EWG’s analysis shows wide variations in water quality. Generally, large water utilities test more often and supply water with lower levels of common pollutants than smaller utilities. But even some large utilities’ water is contaminated with multiple pollutants at levels that exceed government health guidelines.
EWG Rated the Water Utilities
EWG rated big city (population over 250,000) water utilities based on three factors: the total number of chemicals detected since 2004; the percentage of chemicals found of those tested; and the highest average level for an individual pollutant, relative to legal limits or national average amounts for the most common pollutants (disinfection byproducts, nitrate and arsenic). [read more on rating methodology]