EPA proposes rescinding SDWA PFHxS/PFNA/GenX (HFPO-DA) and Hazard Index

EPA has proposed to rescind drinking-water regulatory determinations and remove related requirements tied to three specific PFAS chemicals—PFHxS, PFNA, and GenX (HFPO-DA)—and to a Hazard Index mixture that also includes PFBS. The agency says the action is meant to correct an earlier Safe Drinking Water Act (SDWA) process problem, not to declare that PFAS risks are gone.

This matters for residents because these SDWA determinations were used in EPA’s 2024 PFAS National Primary Drinking Water Regulations (NPDWR) to support requirements that could drive monitoring and, where needed, treatment decisions by public water systems (PWSs). For this proposal, the key question is what changes—if any—after EPA reviews the public record and moves to a final rule.

What EPA proposed (and what it says is the reason)

In a May 20, 2026 Federal Register notice, EPA proposes to:

• Rescind regulatory determinations for these four SDWA-linked items (PFHxS, PFNA, GenX/HFPO-DA, and the Hazard Index mixture including PFBS).
• Rescind associated regulatory provisions that were codified in the 2024 PFAS NPDWR exclusive to these PFAS.
• That includes final MCLs and MCLGs (Maximum Contaminant Levels/Maximum Contaminant Level Goals) and other linked provisions that would have required monitoring, and where necessary, treatment.

EPA frames the rationale as a legal/procedural correction: the agency says the earlier approach treated the determinations and regulations as if they could be handled simultaneously and in tandem, but EPA argues SDWA does not authorize that sequencing.

Timeline: when people could comment, and where the record lives

• May 20, 2026: EPA published the proposed rule in the Federal Register (docket ID EPA-HQ-OW-2025-0654).
• July 7, 2026: EPA held a virtual public hearing as part of the process.
• July 20, 2026: written comments closed.

The Federal Register page also reports that 53,645 comments had been received at Regulations.gov for this docket. Comments are no longer being accepted, so the next turning point is EPA’s review of the record and whether EPA issues a final decision.

What could change next for water systems (if EPA finalizes rescission)

This proposal is not yet a final rescission. But if EPA finalizes it as proposed, the most immediate real-world change would be the removal of the specific SDWA-linked requirements for these PFAS and that Hazard Index framework—potentially affecting what federal provisions would require (or no longer require) in terms of system testing/monitoring and, where needed, treatment.

Even then, implementation isn’t purely federal. SDWA is carried out through a combination of federal standards and state “primacy” oversight, so local impacts depend on how regulators and utilities respond after EPA issues a final rule.

What residents should watch for now

• EPA’s next action: look for a final rule or additional steps that either confirm, narrow, or revise the proposed rescission.
• State/regulator guidance: primacy agencies may adjust how they interpret or plan for testing and compliance while EPA considers final action.
• Utility communications: some public water systems may update sampling or reporting plans in anticipation of possible changes.

Bottom line: EPA’s May 20 proposal targets PFHxS, PFNA, GenX (HFPO-DA), and the Hazard Index mixture including PFBS. The comment window closed July 20, and the public record now sets up EPA’s decision on whether to finalize rescission of these SDWA-linked determinations and related MCL/MCLG provisions—steps that could reshape what federal compliance requirements apply next.

Sources

• EPA — Proposed PFAS Rescission Rule (overview page, hearing/comment info)
• Federal Register — Proposed Rule 2026-10085 (EPA-HQ-OW-2025-0654), published May 20, 2026
• GovInfo — Federal Register PDF for 2026-10085 (official published text)
• Regulations.gov — Docket EPA-HQ-OW-2025-0654 (public comments and documents)