ClearWater › PFAS Rescission
EPA has proposed removing three PFAS limits. 230 water systems currently exceed one of them.
What EPA proposed
On 18 May 2026 EPA announced a proposed rulemaking to rescind the regulatory determinations and drinking water regulations for PFHxS, PFNA, HFPO-DA (GenX), and the Hazard Index mixture of those three PFAS plus PFBS. Each currently carries an enforceable Maximum Contaminant Level of 10 parts per trillion, set in April 2024; the Hazard Index MCL is 1, unitless.
The MCLs for PFOA and PFOS (4 ppt each) are not part of this proposal. EPA has separately proposed extending their compliance deadline from 2029 to 2031.
EPA's stated reason
"The EPA's proposal is necessary to correct the unlawful procedure under which regulations for these PFAS were promulgated. The EPA's proposal is solely based on a need to correct this unlawful process."
EPA further states that once the rescission is final it "will take steps to follow through on its commitment to evaluate additional PFAS in drinking water for future regulation," and that while it "cannot pre-determine the outcome, it is possible that the result could be more stringent requirements."
What EPA's own monitoring data shows
Under UCMR 5, EPA required public water systems to monitor for 29 PFAS between 2023 and 2025. Of the 3,539 systems with PFAS results in that dataset, these are the counts that exceed each limit proposed for rescission:
| Limit proposed for rescission | Systems above it | Notes |
|---|---|---|
| PFHxS — MCL 10 ppt | 171 | Perfluorohexane sulfonic acid |
| PFNA — MCL 10 ppt | 21 | Perfluorononanoic acid |
| HFPO-DA (GenX) — MCL 10 ppt | 16 | Hexafluoropropylene oxide dimer acid |
| Hazard Index — MCL 1 (unitless) | 196 | Of 756 systems with two or more of PFHxS, PFNA, GenX, PFBS |
| Distinct systems above at least one | 230 | Some systems exceed more than one limit |
The 230 systems, by state
Each identifier links to that system's full report.
PFAS Rescission: Frequently Asked Questions
What did EPA propose?
On 18 May 2026 EPA proposed to rescind the regulatory determinations and drinking water regulations for PFHxS, PFNA, HFPO-DA (GenX) and the Hazard Index mixture of those three PFAS plus PFBS. The MCLs for PFOA and PFOS are not part of this proposal, though EPA has separately proposed extending their compliance deadline to 2031.
Why is EPA proposing this?
In EPA's words, the proposal "is necessary to correct the unlawful procedure under which regulations for these PFAS were promulgated" and "is solely based on a need to correct this unlawful process." EPA states that after finalising the rescission it will evaluate additional PFAS for future regulation, and that the result "could be more stringent requirements."
Are these limits still in force?
Yes. The April 2024 regulation remains in effect while the proposal is pending. Nothing has been rescinded yet.
How many water systems would be affected?
Using EPA's own UCMR 5 monitoring data, 230 public water systems have reported a result above at least one of the limits proposed for rescission. This counts the highest single detection reported for each system, not the running annual average EPA uses to determine compliance.
Can the public comment?
EPA is accepting written comments until 2026-07-20 in docket EPA-HQ-OW-2025-0654 at regulations.gov.
Sources
- EPA — Proposed PFAS Rescission Rule
- Federal Register — Proposed Rule (20 May 2026)
- Docket EPA-HQ-OW-2025-0654
- EPA — Final PFAS National Primary Drinking Water Regulation (April 2024)
- EPA — UCMR 5 occurrence data
Page generated 2026-07-10 from EPA data. ClearWater takes no position on the proposed rule.