EPA Announces Plan to Modify PFAS Drinking Water Rule and Extend Compliance Deadline

On May 14, 2025, the U.S. Environmental Protection Agency (EPA) announced its latest plans to address PFAS contamination in drinking water. Specifically, the EPA plans to retain the National Primary Drinking Water Regulation (NPDWR) for PFOA and PFOS at four parts per trillion (ppt) individually, while also extending the associated compliance deadline. Water systems would now have until 2031 to meet the drinking water standards for PFOA and PFOS, allowing for two additional years beyond the original 2029 compliance deadline. 

The EPA is also planning to rescind and reconsider its decision to individually regulate several additional PFAS chains as a part of this rule. EPA aims to rescind the maximum contaminant levels (MCLs) for PFHxS, PFNA, and HFPO-DA (GenX Chemicals) set at 10 parts per trillion (ppt) individually, as well as the novel Hazard Index (HI) MCL for any combination of PFHxS, GenX Chemicals, PFNA, and PFBS. EPA argues that this move is necessary to ensure these determinations and subsequent regulations adhere to the legal framework of the Safe Drinking Water Act (SDWA).

The EPA plans to issue a proposed rule this fall to formalize the extended compliance timeline for PFOA and PFOS, with a final rule expected in spring 2026.

In addition to this extension of the compliance deadline and the reconsideration of the other PFAS MCLs and Hazard Index, EPA is also establishing the PFAS OUTreach Initiative (PFAS OUT). PFAS OUT is intended to have more support for communities, especially rural and small communities. Through the PFAS OUT initiative, the EPA seeks to work with every public water utility with known needs for capital improvements to address PFAS. PFAS OUT will provide funding and technical assistance to be able to assist communities in coming into compliance with the MCLs. 

Additionally, the EPA announced plans to establish a federal exemption framework and is exploring broader regulatory strategies, such as effluent limitation guidelines (ELGs) for PFAS and liability reforms, aimed at supporting utilities while holding polluters accountable.

Despite its plan to rescind part of the rule, the EPA plans to defend the NPDWR with respect to PFOA and PFOS in ongoing litigation from utilities and industry groups. These challengers argue the EPA improperly calculated the costs and benefits of the rule and bypassed legal requirements for standard-setting under the SDWA. The U.S. Court of Appeals for the District of Columbia Circuit previously granted the EPA two litigation stays in this case — first for 60 days and then for 30 days — to give the new EPA leadership time to review the underlying rule and decide on how to proceed in the case. On May 13, 2025, the EPA requested a third stay for an additional 21 days to allow more time to finalize its response to compliance challenges faced by water providers and to coordinate next steps with the involved parties.

The stay and ongoing review come after significant concerns raised by water agencies, which urged the Trump Administration to pause or revise the rule. Some environmentalists and public health advocates, however, argue that rolling back the rule would violate the SDWA's anti-backsliding provision, which prohibits weakening standards for drinking water. The “anti-backsliding” provision has yet to be litigated in court.

Background

On April 10, 2024, the EPA issued a final NPDWR for six PFAS. The regulation imposed MCLs and monitoring requirements for the nation’s water systems for six PFAS chemicals under the SWDA. The final rule set the following MCLs:

The final rule also sets an MCL that uses a HI approach for any combination of PFHxS, GenX Chemicals, PFNA, and PFBS. Under the HI approach, a combination of two or more of those PFAS chemicals can exceed the Maximum Contaminant Level based on the fractions of detected amounts compared to 10 ppt for PFHxS, GenX Chemicals, and PFNA, and compared to 2000 ppt for PFBS. Although the EPA has used a HI approach under other statutes, its use is new under the SDWA. The current final regulation requires water systems to comply with PFAS monitoring and reporting requirements by 2027 and to comply with the MCLs by 2029.

For more information and to address any questions, contact members of BBK’s Environmental Law & Natural Resources practice group.

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