According to a U.S. Geological Survey (USGS) study published on October 24, 2024, approximately 71 to 95 million people in the lower 48 states may rely on groundwater that contains detectable concentrations of per- and polyfluoroalkyl substances (PFAS) for their drinking water supplies.
USGS states that their scientists are the first to report national estimates of PFAS occurrence in untreated groundwater that supplies water to public and private wells. The research also provides the first estimate of the number of people across the county who are potentially affected by PFAS contaminated groundwater.
USGS also published an interactive map for users to see probability estimates of PFAS occurrence.
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.
PFAS in groundwater
The model does not include estimates of PFAS concentrations; testing is the only way to confirm the presence of contaminants.
“This study’s findings indicate widespread PFAS contamination in groundwater that is used for public and private drinking water supplies in the U.S.,” USGS Research Hydrologist and lead author of this study Andrea Tokranov said in a press release. “This new predictive model can help prioritize areas for future sampling to help ensure people aren’t unknowingly drinking contaminated water. This is especially important for private well users, who may not have information on water quality in their region and may not have the same access to testing and treatment that public water suppliers do.”
States with the highest concentrations of PFAS in groundwater supplies
According to the study, the states with the largest populations relying on public water supplies with potentially contaminated groundwater sources are Florida and California. The states with the largest populations relying on private wells with potentially contaminated groundwater are Michigan, Florida, North Carolina, Pennsylvania, New York and Ohio.
USGS states that scientists present separate estimates for public and private wells because they typically receive water from different groundwater depths. Public wells using groundwater as the primary source are usually deeper than private wells.
This research provides a broad outlook for the lower 48 states and presents state-level estimates.
Scientists did not look in detail at specific cities or provide estimates for the types of PFAS present or PFAS concentrations.
