On March 14, 2023, the EPA took a step toward imposing federal limits on certain per- and polyfluoroalkyl substances in drinking water under the Safe Drinking Water Act.
The United States Environmental Protection Agency ("EPA") announced on March 14, 2023, a proposed rule to establish limits on six per- and polyfluoroalkyl substances ("PFAS") known to occur in drinking water. If finalized, it will establish drinking water standards, referred to as Maximum Containment Levels ("MCLs"), and health-based Maximum Contaminant Level Goals ("MCLGs") for:
- Perfluorooctanoic acid ("PFOA");
- Perfluorooctane sulfonic acid ("PFOS");
- Perfluorononanoic acid ("PFNA");
- Hexafluoropropylene oxide dimer acid ("HFPO-DA," also known as Gen X chemicals);
- Perfluorohexane sulfonic acid ("PFHxS"); and
- Perfluorobutane sulfonic acid ("PFBS").
EPA is proposing MCLGs for PFOA and PFOS of zero, and under the National Primary Drinking Water Regulation ("NPDWR"), the agency will limit PFOA and PFOS to 4.0 parts per trillion, what EPA claims is the lowest reliably measurable levels for drinking water. The other four PFAS—PFNA, HFPO-DA, PFHxS, and PFBS—will be regulated as individuals and mixtures using the Hazard Index approach.
In addition, the PFAS NPDWR would require public water systems that have "at least fifteen service connections or regularly serve at least twenty-five individuals" to monitor their PFAS contaminant levels and adhere to the MCLs for all six regulated chemicals. Such public water systems would also need to provide public notice in the event of any NPDWR violation. EPA announced that it expects to finalize the proposed rule by the start of next year. EPA will accept comments for 60 days following publication in the Federal Register.
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