EPA Announces Modifications To National Drinking Water Regulations

Key Takeaways

While EPA has proposed modifications to certain PFAS drinking water regulations, the PFOA and PFOS limits remain firmly in place, and EPA has signaled that a restarted rulemaking process could yield additional requirements for the rescinded compounds in the future.

On May 18, 2026, the U.S. Environmental Protection Agency (“EPA”) proposed two rules that would scale back previously announced drinking water regulations for per- and polyfluoroalkyl substances (“PFAS”). If implemented, these proposals would rescind Maximum Contaminant Levels (“MCLs”) for certain types of PFAS and would allow water systems to seek extensions of the April 2029 deadline for compliance with the National Primary Drinking Water Regulations (“NPDWR”). Notably, these proposals do not affect the MCLs of 4 parts per trillion for perfluorooctanoic acid (“PFOA”) and perfluorooctane sulfonic acid (“PFOS”).

Previously, EPA announced MCLs for four PFAS in addition to PFOA and PFOS. Specifically, these MCLs were for perfluorohexane sulfonic acid, perfluorononanoic acid, hexafluoropropylene oxide dimer acid, and mixtures of these chemicals combined with perfluorobutane sulfonic acid. EPA acknowledged in its press release that the rescission would “address some stakeholders’ legal concerns” that the original rulemaking failed to comply with the Safe Drinking Water Act. Those concerns are being actively litigated: the American Water Works Association has challenged EPA’s rulemaking as arbitrary and “contrary to the plain language” of the SDWA. See Brief of Petitioner at 14–15, Am. Water Works Ass’n v. EPA, No. 24-1376 (D.C. Cir. Oct. 7, 2024). Although these rescissions would ease PFAS requirements in the short term, EPA stated that it intends to restart the process to first evaluate whether regulations are appropriate and then potentially propose a specific regulation. EPA noted that “it is possible that the result could be more stringent requirements.”

The second proposed rule would allow water systems to opt into an extended NPDWR compliance deadline of 2031, a two-year extension of the current April 2029 deadline. Water systems that do not apply for or qualify for the extension would remain subject to the 2029 deadline.

EPA is currently accepting public comments on the MCL rescission and the proposed extension until July 20, 2026. EPA will also hold a public hearing on July 7, 2026.