EPA Announces Plans To Revisit Certain PFAS Drinking Water Standards

Two weeks after U.S. Environmental Protection Agency (EPA) Administrator Zeldin outlined the agency's PFAS plan in broad strokes, EPA provided more detail on how it intends to proceed with respect to drinking water standards for certain Per- and Polyfluoroalkyl Substances PFAS. On May 14, 2025, EPA announced that it will "keep the current National Primary Drinking Water Regulations (NPDWR) for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS)" but intends "to rescind the regulations and reconsider the regulatory determinations for PFHxS, PFNA, HFPO-DA (commonly known as GenX), and the Hazard Index mixture of these three plus PFBS." Under the Biden administration, EPA set the NPDWRs, or maximum contaminant levels (MCLs), at 4 parts per trillion (ppt) each for PFOA and PFOS, 10 ppt each for PFHxS, PFNA, and HFPO-DA, and a Hazard Index of 1 for a combination of two or more of PFHxS, PFNA, HFPO-DA, and PFBS. The PFAS NPDWR was the first time EPA used