Executive Summary
On May 18, 2026, EPA published two proposed rules on PFAS in drinking water. The first would rescind the 2024 federal drinking water limits for four PFAS substances: PFHxS, PFNA, HFPO-DA (commonly known as GenX chemicals), and the Hazard Index for mixtures of those three plus PFBS. EPA’s stated rationale is that the original regulatory process for those four substances violated the Safe Drinking Water Act’s required sequencing. The second proposed rule would allow water systems facing financial or technical hardship to request a two-year extension on compliance with PFOA and PFOS limits, moving the deadline from April 2029 to April 2031. The 4 parts per trillion limit for PFOA and PFOS individually is not changed. Comments closed July 20, 2026. Both rules are proposed and not yet final.
What Happened
EPA’s 2024 National Primary Drinking Water Regulation established enforceable limits for six PFAS: PFOA and PFOS at 4 ppt each, plus individual limits for PFHxS and PFNA and a limit for HFPO-DA (GenX), along with a Hazard Index for mixtures of those three plus PFBS. The 2024 rule required all public water systems to complete initial monitoring by 2027 and achieve compliance with all six limits by April 2029.
The current EPA identified a procedural defect in how the 2024 rule was developed for the four index PFAS. Under EPA’s reading of the Safe Drinking Water…
