USGS Estimates at Least 45% of US Tap Water Contains PFAS

At a Glance

Drinking water quality and sustainability of drinking water supplies are an increasing concern throughout the United States due to population and irrigation-driven water demands.  The U.S. Geological Survey (USGS), the science arm of the Department of Interior, conducted a national water supply survey to assess exposure to per- and poly-fluoroalkyl substances (PFAS) from both private wells and public water supplies. 

PFAS are a class of compounds consisting of thousands of substances that are national/global human health concerns due to their prevalence and persistence in the environment, extremely low regulatory thresholds, and uses in a multitude of products.  These data, along with the Environmental Protection Agency (EPA) ongoing Monitoring Unregulated Contaminants in Drinking Water (UCMR 5, 2022 – 2026) sampling requirements by water supplies, will be used to assess PFAS contamination of drinking-water resources, providing a better understanding of the potential human health consequences associated with exposure.     
USGS scientists collected samples from 716 locations (269 private wells and 447 public water supplies) between 2016 and 2021. These samples represented a range of low, medium, and high human-impact areas. The "low” category included protected lands (public lands and parks, wilderness areas, wildlife refuges, reserves, and conservation easements); “medium” included residential and rural areas with no known PFAS sources; and “high” included urban areas and locations with reported PFAS sources such as industry or waste sites. 

The study tested for 32 individual PFAS compounds using a USGS National Water Quality Laboratory testing method with PFBS, PFHxS and PFOA being most frequently detected.  Other compounds were also detected, exceeding applicable standards.  The report concluded that the greatest exposure was in those urban areas along the Eastern Seaboard, Great Lakes, Central/Southern California and the Great Plains. Currently, regulatory agencies (EPA and individual states) are reviewing and revising their PFAS health advisory levels.  

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