
USGS national estimates of the probability for PFAS in groundwater at the depth of private drinking water supply. Source: USGS
Estimates according to a new USGS predictive model. Exposure to some PFAS may lead to adverse health risks.
Contra Costa has some of the highest levels
Approximately 71 to 95 million people in the Lower 48 states – more than 20% of the country’s population – may rely on groundwater that contains detectable concentrations of per- and polyfluoroalkyl substances, also known as PFAS, for their drinking water supplies. These findings are according to a U.S Geological Survey study published Oct. 24. The predictive model results can help members of the public, water suppliers and regulators understand the potential for PFAS contamination, guide future studies and inform strategic planning for water resources. USGS scientists are the first to report national estimates of PFAS occurrence in untreated groundwater that supplies water to public and private wells. This research also provides the first estimate of the number of people across the country who are potentially affected by PFAS-contaminated groundwater. Along with a scientific report, the USGS published an interactive, online map so users can see probability estimates of PFAS occurrence. Note that predictive results are intended to be evaluated at state, regional and national scales rather than at individual household levels. Probability estimates are for the presence of PFAS in groundwater and do not account for any subsequent actions taken by states, municipalities or individuals to treat drinking water. The model does not include estimates of PFAS concentrations; testing is the only way to confirm the presence of contaminants.
Levels of contaminated groundwater in Contra Costa County. Source: USGS PFAS in US Groundwater Interactive Dashboard