On May 18, 2026, the U.S. Environmental Protection Agency (EPA) announced two proposed rules. The first proposed rule would uphold the federal drinking water Maximum Contaminant Levels (MCL) for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) while providing an option for drinking water systems to request two additional years to comply with the enforceable limits. The second proposed rule would rescind the regulatory determinations and regulations for perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA), hexafluoropropylene oxide dimer acid and its ammonium salt (HFPO-DA) (commonly known as GenX chemicals), and Hazard Index mixtures of these three PFAS plus perfluorobutane sulfonic acid (PFBS). EPA will hold consecutive virtual public hearings on July 7, 2026, during which the Agency will present information on the proposed rules and receive verbal comments. Comments are due July 20, 2026. Comments on the information collection provisions of the proposed PFOA and PFOS extension rule under the Paperwork Reduction Act (PRA) must be received by the Office of Management and Budget’s Office of Information and Regulatory Affairs by June 22, 2026.
Background
The Biden EPA issued on April 26, 2024, the final National Primary Drinking Water Regulation (NPDWR) for six per- and polyfluoroalkyl substances (PFAS). 89 Fed. Reg. 32532. The NPDWR established MCLs for PFOA, PFOS, PFHxS, PFNA, and HFPO-DA as contaminants with individual MCLs, and PFAS mixtures containing at least two or more of PFHxS, PFNA, HFPO-DA, and PFBS using a Hazard Index MCL to account for the combined and co-occurring levels of these PFAS in drinking water. EPA also issued final health-based, non-enforceable Maximum Contaminant Level Goals (MCLG) for these PFAS. The final rule required water systems to comply with all MCLs in 2029. More information on the final rule is available in our May 9, 2024, memorandum.
Proposed PFOA and PFOS Compliance Extension Rule
In this proposed rulemaking, EPA proposes a federal exemption, pursuant to Safe Drinking Water Act (SDWA) Sections 1416(f) and 1450(a)(1), that will extend the dates of compliance with the MCLs for PFOA and PFOS from April 26, 2029, to April 26, 2031, for those systems that submit a request. 91 Fed. Reg. 29425. EPA requests comment on this proposal, including the mechanisms through which the MCL compliance deadlines for PFOA and PFOS can be exempted, and has identified specific areas where public input will be helpful for EPA in developing the final rule.
According to questions and answers (Q&A) on EPA’s website, EPA is proposing the extension rule because many water systems need more time to comply with the drinking water limits for PFOA and PFOS. EPA states that to protect public health and instill confidence that drinking water is safe, drinking water systems addressing PFOA and PFOS generally require:
- Robust drinking water quality data to diagnose the severity of contamination;
- An understanding of compliance options, including changing source-water or installing new controls to remove PFOA and PFOS;
- Time to construct and test new controls;
- A financing plan to invest in system changes while supporting fiscal responsibility and water affordability for customers; and
- A workforce dedicated to supporting construction, operation, and maintenance.
EPA states that if the 2029 deadline is not extended, costly violations could be levied that would only “add paperwork and fees that distract from focused efforts on reducing exposure to PFOA and PFOS.” EPA notes that extra time also allows “the cost of PFOA and PFOS removal technologies to come down via technological advancements and production efficiencies.”
Proposed Rule to Rescind Regulatory Determinations and Regulations for PFHxS, PFNA, HFPO-DA, and Hazard Index Mixtures
EPA proposes to rescind its regulatory determinations to regulate four PFAS — PFHxS, PFNA, HFPO-DA, and mixtures of these three PFAS plus PFBS — under the SDWA. 91 Fed. Reg. 29413. EPA also proposes to rescind all associated regulatory provisions currently codified in the EPA’s 2024 NPDWR exclusive to these PFAS that were promulgated pursuant to the regulatory determinations that EPA now proposes to rescind, including the final MCLs that would have required monitoring, and where necessary, treatment by public water systems (PWS). According to EPA, this proposed action is necessary to correct the unlawful procedure under which these regulations were promulgated. Under EPA’s prior interpretation, the Agency proposed and issued final regulatory determinations and regulations for these PFAS simultaneously and in tandem. EPA states that “[u]nder the best reading of the statute, the EPA is not authorized to take such actions simultaneously and therefore, the Agency proposes to rescind those regulatory determinations, [MCLGs] and associated portions of the 2024 PFAS NPDWR.”
EPA seeks public comment on:
- The legal interpretation of “determination to regulate” as used in SDWA Section 1412(b)(1)(E);
- The rescission of the regulatory determinations for PFHxS, PFNA, HFPO-DA, and the Hazard Index PFAS;
- EPA’s economic analysis in the associated memorandum, including additional costs, cost savings, benefits, and forgone health benefits of the action; and
- The rescission of associated MCLGs, MCLs, and related regulatory provisions from 40 C.F.R. Part 141.
EPA notes that it is proposing this rulemaking solely on legal grounds. Comments not limited to the basis of EPA’s proposal or specific regulatory edits associated with removing requirements related to PFHxS, PFNA, HFPO-DA, and the Hazard Index PFAS from the C.F.R. are considered beyond the scope of this rulemaking. EPA states that it is not seeking comment on its substantive findings supporting either its regulatory determinations or its associated NPDWR provisions, including any information about health risks associated with PFAS, cost of regulation, or occurrence information. According to a Q&A on EPA’s website, once EPA has taken final action to rescind the current regulations for PFHxS, PFNA, HFPO-DA, and Hazard Index mixtures of these three PFAS plus PFBS, the Agency “will take steps to follow through on its commitment to evaluate additional PFAS in drinking water for future regulation. While the EPA cannot pre-determine the outcome, it is possible that the result could be more stringent requirements.”
Commentary
In our memorandum on the 2024 NPDWR, we acknowledged “the significant differences of scientific opinion that exist on the data EPA relied upon as the basis for informing its MCLs/MCLGs.” EPA stated in the final rule, however, that the “final rule represents data-driven drinking water standards that are based on the best available science and meet the requirements of SDWA.” In its announcement, EPA describes the issue with the MCLs for PFOA and PFOS as one of compliance. If the first proposed rule is issued in final, it would continue supporting the health-protective federal drinking water standards for PFOA and PFOS “while strengthening practical implementation by establishing an opt-in process through which eligible drinking water systems may apply for up to two additional years — until 2031 — to come into compliance with enforceable limits.” EPA states that allowing drinking water systems to seek additional time “could also allow the cost of PFAS removal technologies to come down through technological advancements and production efficiencies.” According to EPA, “[c]ontinued federal investment, paired with a growing market for treatment technologies, is already driving costs down, better informing water utilities about what works, and expanding the toolkit available to remove PFAS in its various forms.” As EPA notes, the second proposed rule, if issued in final, would address some legal concerns regarding EPA’s combination of steps under the SDWA to regulate additional PFAS.
EPA’s announcement highlights other actions that the Agency is taking, such as “advancing technology-based effluent limitations and pretreatment standards for key industrial categories that discharge PFAS, including chemical manufacturers and other sources, to keep PFAS out of waterways.” EPA intends to issue a proposed rule “in the coming months.” EPA states that it is also using its Toxic Substances Control Act (TSCA) authorities “to ensure new and existing chemicals are subject to the most robust, gold-standard scientific review before they enter commerce.” EPA notes that it seeks to hold polluters accountable for legacy contamination consistent with the polluter-pays principle, rather than the passive receivers. Because EPA’s enforcement discretion policy alone cannot shield passive receivers from third-party cleanup lawsuits, EPA concludes that “a durable statutory fix from Congress is necessary.”
