EPA Proposes to Rescind PFAS Drinking Water Rules for Four Substances - PFHxS, PFNA, GenX, and PFBS Mix
EPA is proposing to rescind its regulatory determinations for four per- and polyfluoroalkyl substances (PFAS) under the Safe Drinking Water Act. The proposed rule would eliminate drinking water regulations for perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA), hexafluoropropylene oxide dimer acid (HFPO-DA, known as GenX chemicals), and mixtures of these three PFAS plus perfluorobutane sulfonic acid (PFBS). EPA is also proposing to remove all associated regulatory provisions from its 2024 PFAS National Primary Drinking Water Regulation.
What the Proposed Rule Changes
The rescission would eliminate specific regulatory requirements for these four PFAS substances that were established in EPA’s comprehensive 2024 PFAS drinking water rule. The proposal removes:
- Maximum contaminant levels (MCLs): Specific drinking water limits for PFHxS, PFNA, GenX chemicals, and the PFBS mixture
- Monitoring requirements: Public water system testing obligations for these four substances
- Treatment technology specifications: Required treatment methods for removing these PFAS from drinking water supplies
- Public notification requirements: Mandatory disclosure when these substances exceed regulatory thresholds
What this means in practice: Public water systems would no longer be required to monitor for or treat these four PFAS substances specifically, though PFOA and PFOS regulations remain in effect.
How This Affects Site Remediation Work
CERCLA and RCRA Corrective Action Sites
Federal cleanup sites often use drinking water standards as cleanup targets for groundwater remediation. If EPA finalizes this rescission, these four PFAS substances would lose their federal drinking water benchmarks. Site managers would need to identify alternative cleanup targets, potentially relying on state standards or risk-based calculations.
State Program Implications
Many state cleanup programs reference federal drinking water standards in their regulatory frameworks. Ohio’s Voluntary Action Program (VAP) and BUSTR programs, for example, often incorporate federal MCLs into their cleanup standards. The rescission could create regulatory gaps where state programs previously relied on federal PFAS drinking water limits.
Groundwater Monitoring Programs
Sites with ongoing groundwater monitoring may need to reassess their analytical programs. While laboratories can still analyze for these four PFAS substances, the regulatory drivers for including them in routine monitoring would be reduced without federal drinking water standards.
What to Watch
EPA has opened a public comment period on the proposed rescission. The agency has not announced a specific timeline for finalizing the rule. State environmental agencies may respond by establishing their own drinking water standards for these four PFAS substances to fill regulatory gaps.
Several states already maintain PFAS drinking water standards that differ from federal requirements. The rescission could accelerate state-level rulemaking for these substances.
What to Do Now
If you work on sites with PFAS contamination, review your current cleanup targets for PFHxS, PFNA, GenX chemicals, and PFBS mixtures. Identify whether your cleanup standards rely on federal drinking water limits that could be eliminated. For ongoing remediation projects, consider discussing alternative cleanup targets with regulators before EPA finalizes any rescission.
Check state-specific PFAS standards that may remain in effect regardless of federal action. Review our PFAS standards comparison and Ohio PFAS groundwater standards for current regulatory requirements.