The EPA proposed cutting its PFAS drinking water rule in half today. Here's what would actually be enforceable if it becomes final.

The EPA published two proposed rules today, May 18, 2026, that together would roll back roughly half of the PFAS drinking water regulation finalized two years ago. Neither has been finalized yet — they’re proposed rules entering public comment — but the direction of travel is now explicit, and it changes what’s actually federally enforceable about per- and polyfluoroalkyl substances in your tap water.

This piece is the factual rundown. What the original 2024 rule did, what the new proposals would change, what stays, what goes, where state regulators fill the federal gap, and what any of this means for a homeowner deciding whether to install a filter.

What the 2024 rule actually established

The EPA finalized the PFAS National Primary Drinking Water Regulation on April 10, 2024, with the rule taking effect on June 25, 2024. It was the first federal enforceable drinking water standard for any PFAS compound and it covered six items:

• PFOA (perfluorooctanoic acid) — Maximum Contaminant Level (MCL) of 4 parts per trillion (ppt)
• PFOS (perfluorooctane sulfonic acid) — MCL of 4 ppt
• PFHxS (perfluorohexane sulfonic acid) — MCL of 10 ppt
• PFNA (perfluorononanoic acid) — MCL of 10 ppt
• HFPO-DA (hexafluoropropylene oxide dimer acid, also known as “GenX chemicals”) — MCL of 10 ppt
• Hazard Index mixture of PFHxS, PFNA, HFPO-DA, and PFBS (perfluorobutane sulfonic acid) — a unitless index calculation, where the combined ratio of measured concentrations to reference values must remain below 1.0

The original timeline required public water systems to complete initial monitoring by 2027 and to comply with the MCLs by April 2029. The rule was projected by the EPA to reduce PFAS exposure for approximately 100 million people nationwide and was widely characterized at the time as the most consequential federal drinking water standard in over a decade.

What the May 2026 proposals would change

The EPA published two separate proposed rules today.

Proposed PFOA and PFOS Compliance Extension Rule. This proposed rule does not change the 4 ppt MCLs for PFOA or PFOS. It would, however, allow public water systems to request an additional two years to comply, moving the practical compliance deadline for those two compounds from April 2029 to April 2031. Monitoring requirements would also be allowed an additional two years. The EPA frames this as a practical implementation accommodation for utilities that need more lead time for capital improvements.

Proposed PFAS Rescission Rule. This second proposed rule would entirely rescind the MCLs set in 2024 for four of the six covered items: PFHxS, PFNA, HFPO-DA (GenX), and the Hazard Index mixture. The agency’s stated rationale is that the original 2024 rulemaking did not follow the regulatory procedures the agency now believes are required under the Safe Drinking Water Act for those specific compounds. The proposed rule withdraws the enforceable limits without proposing replacement values.

Both proposed rules are now in public comment. If finalized as proposed, the federal regulatory floor for PFAS in drinking water would consist of only two compounds — PFOA and PFOS — at 4 ppt each, with a compliance deadline of 2029 with optional extension to 2031.

What would still be true federally

Even if both proposed rules become final, the following remain in effect:

• PFOA at 4 ppt MCL. This is a tight standard by international comparison. The WHO’s 2022 provisional guideline value is 100 ppt; the EU’s 2020 directive sets a sum-of-twenty PFAS at 100 ppt total.
• PFOS at 4 ppt MCL. Same comparative note.
• Monitoring and public notification requirements for the regulated compounds. Utilities must measure PFOA and PFOS, report results, and notify customers when limits are exceeded.
• The Safe Drinking Water Act framework itself. The EPA retains authority to revisit any of the rescinded compounds and to add other PFAS in the future. Several PFAS — including PFHxS, PFNA, and GenX — remain on the EPA’s contaminant candidate list, which means future regulation is possible even if the current MCL is withdrawn.

What would no longer be federally enforceable

If the rescission becomes final:

• PFHxS: previously regulated at 10 ppt MCL. No federal enforceable limit.
• PFNA: previously regulated at 10 ppt MCL. No federal enforceable limit.
• HFPO-DA (GenX): previously regulated at 10 ppt MCL. No federal enforceable limit.
• Hazard Index mixture: the combined-effects calculation covering the four compounds above plus PFBS. No federal enforceable limit.

For these four items, after a final rescission, federal regulation would revert to the pre-2024 status — meaning the EPA could issue health advisories (non-binding) but utilities would not be required to test for, treat for, or report these compounds at the federal level.

State regulators have been filling the gap longer than the federal rule has existed

For drinking water enforcement specifically, several states regulated PFAS before the EPA did, and their rules don’t change regardless of what the federal proposals do.

New Jersey was the first state to set enforceable MCLs for PFAS. The NJDEP established 13 ppt for PFNA in 2018 and added 14 ppt for PFOA and 13 ppt for PFOS in 2020. Notably, New Jersey’s PFNA MCL is the kind of compound-specific limit the federal rescission would eliminate at the federal level. Within New Jersey, the state MCL remains enforceable.

Michigan issued MCLs in 2020 covering seven PFAS compounds, including PFOA at 8 ppt and PFOS at 16 ppt. EGLE (Michigan’s environmental agency) indicated in 2024 that it intends to lower Michigan’s MCLs at or below federal levels on or before 2026.

Massachusetts regulates a sum-of-six PFAS at 20 ppt combined, an approach distinct from per-compound MCLs.

California is a partial exception worth understanding clearly. California has set Public Health Goals (PHGs) for PFOA at 0.007 ppt and PFOS at 1 ppt — values dramatically lower than the federal 4 ppt and among the strictest in the world. PHGs in California are non-enforceable health targets, not MCLs. California’s enforceable drinking water program uses Notification Levels (4 ppt for PFOA, 4 ppt for PFOS) and Response Levels (10 ppt PFOA, 40 ppt PFOS) — which trigger reporting and disclosure requirements but are not MCLs in the federal sense. As of May 2026, California has not yet promulgated state-level enforceable MCLs.

At least a dozen other states have either MCLs, notification levels, or PFAS response frameworks of varying stringency. The American Water Works Association maintains a current state-by-state tracker for utilities; for consumers, your state environmental agency’s drinking water program is the best source for what’s enforceable in your specific service area.

What the federal proposed rules mean for your tap water — practically

The honest answer depends on three things.

One: where do you live. If you’re served by a public water system in New Jersey, Michigan, Massachusetts, or one of the other states with enforceable state-level PFAS rules, the federal rescission would not change what your utility has to do. State MCLs continue to bind state-permitted public water systems. If you’re in a state that has relied entirely on the federal rule, the rescission of four of six compounds means your utility would no longer be required to test for or treat for those four compounds at the federal level after the rule is finalized — though the EPA could issue non-binding health advisories that some utilities choose to follow.

Two: what is the actual PFAS profile of your source water. Some source waters have detectable PFOA and PFOS but not the other four covered compounds, in which case the rescission has minimal practical effect. Other source waters — particularly those near manufacturing sites with historical GenX use, certain military bases with AFFF firefighting foam contamination, and some agricultural areas — have detectable PFNA, PFHxS, or GenX in greater concentrations than PFOA or PFOS. For those communities, the rescission removes the federal regulatory mechanism for the contaminants that actually exist in their tap water. State and local responses remain.

Three: what does your Consumer Confidence Report actually say. PFAS were added to the EPA’s Unregulated Contaminant Monitoring Rule (UCMR) cycle starting in 2023, which means many utilities have begun collecting PFAS data even if they weren’t yet required to act on it. Some CCRs now include detected PFAS values. If yours does, you have actual numbers to evaluate against the surviving federal MCLs (PFOA and PFOS) and against state rules where applicable. If yours doesn’t, your state’s drinking water program likely maintains a separate PFAS dashboard.

The piece we already published on reading a Consumer Confidence Report covers how to actually parse one. The PFAS section of that piece has been updated to reflect the May 2026 proposals.

What this means for filtration

Federal regulation of a contaminant and consumer-level filtration of that contaminant are independent decisions. A federal rescission doesn’t change what’s in your water; it changes what your utility is required to do about it. If PFAS removal at the tap was worth doing yesterday because of what’s in your source water, it’s worth doing tomorrow regardless of what the federal rule looks like.

The technologies that actually reduce PFAS — granular activated carbon, ion exchange, and reverse osmosis — work regardless of regulatory status. NSF/ANSI tests filters against the PFAS-reduction protocols that were originally published as the standalone NSF/ANSI P473 protocol in 2016 and then incorporated into NSF/ANSI 53 (for carbon and ion-exchange systems) and NSF/ANSI 58 (for reverse osmosis systems) in 2017. Those standards were expanded in 2022 to cover six PFAS compounds: PFOA, PFOS, PFHxS, PFNA, PFHpA, and PFBS. The countertop reverse osmosis category in particular (AquaTru and similar systems) is independently certified by IAPMO to those NSF standards, with PFAS reduction documented across the regulated compounds and broader PFAS classes the federal rule never addressed. Gravity-fed systems with activated carbon and ion-exchange media (like the Alexapure Pro we cover) reduce PFAS to varying degrees per element configuration — buyers should pull the per-contaminant test data.

The shopping question post-rescission is the same as the shopping question pre-rescission: what’s in your specific water, what specific contaminants does the filter remove according to independent lab testing, and what’s the total cost of ownership over five years.

What’s next on the regulatory timeline

The EPA is accepting written comments on the proposed Rescission Rule for 60 days in the public docket at regulations.gov under Docket ID EPA-HQ-OW-2025-0654. A virtual public hearing is scheduled for July 7, 2026 where the public can submit verbal comments. The Compliance Extension Rule has its own separate docket. The agency then reviews comments, may make modifications, and issues a final rule — historically that step takes another 6-12 months on rules with significant policy implications and active litigation interest.

Two pieces of organizational opposition are already on the record. Environmental Working Group president Ken Cook characterized the rule as “caving to chemical industry lobbyists and water utility pressure” and said it would “condemn millions of Americans to drink contaminated water for years to come.” NRDC’s Erik D. Olson, the organization’s senior strategic director for health, argued that the Safe Drinking Water Act limits compliance extensions to five years from the original deadline, and that EPA’s proposal to allow two additional years on top of the original five “violate[s] the letter and intent of the law.” Several state attorneys general have indicated they are tracking the rulemaking and may litigate if the final rule rescinds the four PFAS without adequate procedural basis under the SDWA.

The American Chemistry Council and the National Association of Manufacturers had previously filed a joint lawsuit against the EPA challenging the 2024 rule on the grounds that the limits were “arbitrary, capricious and an abuse of discretion.” That lawsuit is currently pending before the US Court of Appeals for the DC Circuit. The chemical industry has, broadly, supported the EPA’s pivot toward rescission.

The practical takeaway: the regulatory state on PFAS will likely remain in flux through at least 2027. State-level rules are the more stable framework for now. Filtration decisions should be based on what’s in your water and what your filter actually removes — not on the federal regulatory framework, which is going to keep moving.

---

This piece was published the same day the EPA announced the two proposed rules. It will be updated if either rule is materially modified in public comment, if a final rule is issued, or if states change their corresponding regulations.