EPA Finalizes Stringent Drinking Water Standards for Five PFAS Chemicals

On April 10, 2024, the Environmental Protection Agency (EPA) issued the first ever National Primary Drinking Water Regulations (NPDWRs), which are legally enforceable national standards, setting limits for five individual PFAS and for mixtures of any two or more of four PFAS:

  • 4.0 parts per trillion (ppt) for PFOA and PFOS, individually
  • 10.0 ppt for PFNA, PFHxS, and “GenX Chemicals,” individually
  • 1.0 Hazard Index for any mixture of two or more of the following PFAS: PFNA, PFHxS, PFBS, and “GenX Chemicals”

These standards are significantly more stringent than Maine’s interim standard of 20 ppt for six PFAS – PFOA, PFOS, PFHxS, PFNA, PFHpA, and PFDA – alone or in combination. 

Under the new rule, water utilities will have five years to comply: three years to test for the six PFAS chemicals and two years to purchase and install any technologies necessary to treat the water. 

The final rule expands upon the EPA’s proposed NPDWR, which was issued in March 2023. For more information about the proposed rule, please see our March 15, 2023 and March 29, 2023 alerts.

The pre-publication version of the rule is available here, and will go into effect 60 days after it is formally published in the Federal Register. For more information about the final rule, or for questions related to its implementation and impact, please contact Pierce Atwood environmental law attorneys Lisa Gilbreath (207.791.1397), Brian Rayback (207.791.1188), or Georgia Bolduc (207.791.1249).