Legal challenges cloud future of PFAS regulation as EPA moves to vacate PFAS MCL

The U.S. Environmental Protection Agency (EPA) has asked a federal appeals court to partially vacate its 2023 drinking water rule for four PFAS compounds, citing procedural missteps in how the agency finalized the regulation. The motion, filed with the U.S. Court of Appeals for the D.C. Circuit, comes in response to litigation brought by industry groups challenging the rule’s legal foundation.

At issue are the Maximum Contaminant Level Goals (MCLGs) and enforceable Maximum Contaminant Levels (MCLs) for PFNA, PFHxS, HFPO-DA (commonly known as GenX), and a category referred to as “ Hazard Index PFAS.” In its filing, EPA acknowledged that it violated the Safe Drinking Water Act by proposing and finalizing both the regulatory determination and the drinking water standards for these chemicals simultaneously. This procedural error, the agency said, deprived stakeholders of a meaningful opportunity to comment on the regulatory determination before the standards were set.

The EPA is not seeking to vacate the rule for PFOA and PFOS, two of the most widely studied and regulated PFAS compounds. The agency maintains that it followed proper statutory procedures for those contaminants and is defending their inclusion in the final rule.

For municipal drinking water utilities, the motion introduces a layer of regulatory uncertainty. If the court grants the vacatur, utilities may need to reassess compliance strategies and monitoring plans for the affected PFAS compounds. In many cases across the U.S., drinking water systems are already paying for, implementing and installing PFAS removal systems to comply with the MCL, including the Hazard Index EPA hopes to vacate.

This motion aligns with EPA's strategic priority update on PFAS from May of this year, which also called for an extension of the compliance deadline. Originally scheduled for April 26, 2029, the agency called for it to be moved to 2031 to give utilities more time to comply, shift priorities for treatment technologies, and plan capital spending.

The legal challenge underscores the importance of procedural transparency in federal rulemaking, particularly for contaminants that carry significant cost and operational implications for water systems. It also reflects a broader trend of legal scrutiny facing EPA regulations, including recent challenges to methane rules and environmental justice grant programs.

Water industry professionals should monitor the outcome of this case closely, and refer to news on regulations within their states. This vacation may influence future regulatory actions at the state level, which would still require compliance by drinking water utilities.

How did we get here?

AWWA petitioners argued that the EPA violated the Safe Drinking Water Act’s procedural requirements in three ways. First, the association argued that EPA simultaneously proposing and finalizing both the regulatory determination and the enforceable standards for four PFAS compounds (PFNA, PFHxS, HFPO-DA, and the Hazard Index mixture). Second, AWWA contends EPA denied stakeholders the opportunity to comment on the regulatory determination before the standards were proposed. And lastly, which has been widely reported in the water market, AWWA questioned the financial component of finalizing and MCL. It claimed the PFAS MCL would impose costly and potentially unfeasible standards without adequate public input or scientific justification.

Read the full motion: AWWA ET AL., Petitioners, v. U.S. Environmental Protection Agency, ET AL., Respondents. On Petition for Review of Actions by Environmental Protection Agency.