On May 1, 2026, the White House Office of Management and Budget (OMB) completed its interagency review and cleared two EPA proposed rules that would scale back the Biden-era PFAS National Primary Drinking Water Regulation (NPDWR). As we previously reported, the proposed rules would extend the compliance deadline for PFOA and PFOS maximum contaminant levels (MCLs) by two years and rescind the MCLs for PFNA, PFHxS, HFPO-DA (commonly known as GenX) and mixtures containing two or more of these compounds and PFBS. With OMB’s review concluded, the proposed rules are cleared for publication in the Federal Register, which is expected to occur in the near future.
The current MCLs, established in April 2024, are 4.0 parts per trillion (ppt) for PFOA and PFOS; 10 ppt for PFNA, PFHxS, and GenX; and a Hazard Index of 1.0 for mixtures of these three compounds and PFBS. Under the current rule, public water systems are required to complete initial monitoring by 2027 and implement treatment systems to meet the MCLs by 2029.
The first proposed rule would extend the compliance deadline for PFOA and PFOS MCLs from 2029 to 2031, giving public water systems an additional two years to implement treatment systems. The second proposed rule would rescind the MCLs for PFHxS, PFNA, HFPO-DA, and the Hazard Index mixture of these three compounds plus PFBS.
These administrative actions are proceeding alongside judicial review in the U.S. Court of Appeals for the D.C. Circuit. On January 21, 2026, the D.C. Circuit denied EPA’s request to summarily vacate the MCLs for PFHxS, PFNA, HFPO-DA, and mixtures with PFBS. On March 23, 2026, the court further denied EPA’s motion to sever and stay challenges to the MCLs for these PFAS. As a result, the existing PFAS MCLs remain in place as both the litigation and the administrative process move forward on parallel tracks.
We will continue to monitor these developments and provide updates as the proposed rules are published and as the D.C. Circuit litigation progresses.