With a new administration in Washington, D.C., the environmental community has been at the edge of its collective seat awaiting word on the fate of one of the most significant elements of EPA's PFAS Strategic Roadmap – the maximum contaminant levels (MCLs) for selected PFAS. The MCLs, following EPA's initial – though unenforceable – PFAS Health Advisory Levels – were promulgated on April 10, 2024, and quickly became the cornerstone of EPA's PFAS regulatory initiative. MCLs not only govern the quality of drinking water, but also are used to derive groundwater standards and clean-up standards across the country.
In a May 14, 2025 press release, EPA gave the first indication of how it intends to proceed. Significantly, the agency stated that it intends to keep in place the existing MCLs of 4 parts per trillion (ppt) for the two most well-known PFAS – PFOS and PFOA – but will extend the initial compliance deadline from 2029 to 2031. EPA claims that this extension is intended to allow water utilities additional time to install any new treatment technologies needed to meet the standards. Despite keeping the MCLs for PFOS and PFOA, EPA also announced its plan to withdraw other elements of the final April 2024 PFAS MCL rule, specifically the regulatory determinations for PFHxS, PFNA, HFPO-DA (commonly known as GenX), and the Hazard Index mixture of those chemicals plus PFBS, pending possible reintroduction this Spring.
EPA's plan has been widely reported by the media and environmental organizations as a retreat on efforts to address PFAS in the nation's drinking water. Yet there are also those in the scientific community who claim that leaving the 4 ppt standards for PFOA and PFOS in effect is extremely significant as it will still drive extensive PFAS reductions nationwide, even if the standards for the other PFAS are temporarily withdrawn. They argue that the PFOA and PFOS standards will still drive the need for new – and expensive – treatment technologies for the vast majority of PFAS-impacted systems across the country, which will significantly reduce overall PFAS levels in drinking water. For example, in data from a group of water treatment systems gathered under the Unregulated Contaminant Monitoring Rule, average PFOA concentrations exceeded the 4 ppt standard in 6% of the systems, and PFOS exceeded the standard in 7.2% of the systems. PFAS National Primary Drinking Water Regulation, 89 Fed. Reg. 32,532, 32,601-02. In contrast, none of the PFAS standards EPA plans to withdraw were exceeded in more than 0.6% of systems. Id. There are those that claim that the types of treatment systems needed to meet the PFOA and PFOS MCLs often also treat other PFAS chemicals found in the water. Thus, they argue that the practical effect of eliminating the MCLs for the other PFAS chemicals may not, at the end of the day, significantly alter the overall net PFAS levels in the nation's water, as long as water systems are still required to implement the type of treatment necessary to meet the new PFOA and PFOS MCLs.
Similarly, it is also being reported that delaying implementation of the PFOA and PFOS MCLs by an additional two years may not have much impact on the pace at which PFAS levels in drinking water systems are actually lowered. Many drinking water systems are already stating that they will not be able to put treatment systems in place by 2029, regardless of what the MCLs require. Thus, it is being argued that the additional two year reprieve will push back any government enforcement, but not necessarily the pace of the nation's water system actually reaching the 4 ppt standards.
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