USGS Releases New Study on PFAS in US Tapwater

The United States Geological Survey (USGS) recently released the results of a five-year study that sampled for per- and polyfluoroalkyl substances (PFAS) in tapwater from both unregulated private-well and regulated public-supply tapwater. USGS collected samples of tapwater from 716 locations (269 private-wells; 447 public-supply) across the US between 2016 and 2021. The results showed seventeen PFAS that were observed at least once. PFBS, PFHxS, and PFOA were the most common, with each being identified in approximately 15% of the samples. With this data, USGS estimates that at least one PFAS could be detected in about 45% of US drinking water samples.

The study notes that the Environmental Protection Agency’s (EPA) proposed MCLs for PFOA and PFOS, at 4 parts per trillion, were exceeded in 63% and 67%, respectively, of the private-well tapwater samples and in 44% and 77%, respectively of the public-supply tapwater samples, when the substances were detected. The study also found that 4.6% of tapwater collected exceeded EPA’s proposed hazard index of 1.0 for the sum of the toxicity quotient (measured concentration/health-based value) for PFBS, PFNA, PFHxS, and GenX.