EPA Proposes Updates to PFAS Drinking Water Regulations

On May 14, EPA published a press release outlining proposed revisions to the Agency’s 2024 Final Ruleestablishing Maximum Contaminant Levels (MCLs) and Maximum Contaminant Level Goals (MCLGs) for six PFAS in drinking water under the Safe Drinking Water Act (SDWA).

EPA stated that it intends to:

• Retain the 4 ppt MCLs for PFOS and PFOA in drinking water.
• Extend the compliance deadline from 2029 to 2031.
• “[R]escind the regulations and reconsider the regulatory determinations” for four other PFAS:
  • perfluorohexanesulfonic acid (PFHxS),
  • perfluorononanoic acid (PFNA),
  • hexafluoropropylene oxide dimer acid (HFPO-DA), and
  • perfluorobutane sulfonic acid (PFBS).

The Final Rule stipulated that PFHxS, PFNA, HFPO-DA, and PFBS would be regulated using a Hazard Index approach for any mixture containing two or more of these PFAS. However, the press release indicates EPA will reevaluate this approach to ensure it “follow[s] the legal process laid out in” the SDWA.

EPA’s press release comes just two days after its request to extend the stay granted by the U.S. Court of Appeals for the District of Columbia Circuit in the lawsuit challenging EPA’s Final Rule. EPA requested additional time to evaluate the Final Rule and the lawsuit.

In briefs filed under the lawsuit, Petitioners argued that:

1. By grouping four of the PFAS together, EPA was unable to fully evaluate the treatment costs and benefits for each PFAS.
2. The SDWA only authorizes EPA to regulate levels of individual substances, not mixtures.
3. Including HFPO-DA in a national regulation was “improper” as this PFAS does not frequently occur in public water systems.

EPA plans to issue a proposed rule in the fall of 2025 and finalize it in Spring of 2026.

Questions? Reach out to Heather Lynch at hlynch@integral-corp.com.