EPA Announces it will Regulate Two PFAS Compounds in Drinking Water

The U.S. Environmental Protection Agency (EPA) announced that it will regulate two polyfluoroalkyl substances (PFAS), specifically perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in drinking water. This determination was based on the agency’s ongoing emerging contaminants program highlighted in the Fourth Drinking Water Contaminants Candidate List.


The EPA reviewed human health and toxicological data for PFOS and PFOA relative to a Health Reference Level (HRL) of 0.07 µg/L. Critical factors in EPA’s decision were


  1. the occurrence of these contaminants above the HRL in drinking water systems, and
  2. the population exposed to these contaminants at the HRL in public water supply (PWS) systems.


The EPA’s decision was also supported by results from multiple states’ PWS monitoring initiative: finished (treated) water data from fifteen states indicated combined PFOS and PFOA concentrations exceeded the EPA’s HRL of 0.07 µg/L in at least 29 large PWS.


In this process of regulating PFOA and PFOS, the EPA is also leading the following efforts per the EPA PFAS Action Plan:

  • Rigorous toxicity assessment studies are being conducted for seven PFAS compounds namely, PFBS, PFBA, PFHxS, PFHxA, PFNA, PFDA, and HFPO-DA (Gen X Chemicals). This assessment is projected to be completed by 2023.
  • Additional information for 29 PFAS compounds in finished drinking water is being collected as part of UCMR5 cycle using Methods 537.1 and 533 for detecting PFAS chemicals at lower reporting levels than previously possible.
  • Efforts are ongoing to develop toxicology data for much larger sets of less-studied PFAS through these new approach methods (NAMS). These methods include screening mechanisms, toxicology tools, and informatics metrics that prioritize screening and risk assessment.

Regulatory determination for additional PFAS compounds is anticipated with the pending Fifth Drinking Water Contaminants Candidate List in 2026.


Find more information in our PFAS Resource Center.