PFAS Drinking Water Rules, Explained (2026)
Six federal PFAS limits remain in force. The EPA has proposed keeping two and rescinding four — and as of mid-2026, those proposals are not final. The exact state of play, with every claim tied to a source.
By Max — Founder, builder of TapGraded's EPA data pipeline · July 12, 2026 · Updated July 18, 2026
Six federal limits on PFAS in drinking water are in force in the United States. On May 18, 2026, the EPA proposed keeping two of them and rescinding the other four. As of this writing, both actions remain proposals — which means the full 2024 regulation still stands, and water systems are still on the clock to comply with it.
That is the whole story in three sentences. The detail below is what each number is, what was proposed, and what happens next.
The 2024 rule set the first federal PFAS limits
On April 10, 2024, the EPA finalized the first National Primary Drinking Water Regulation for PFAS — per- and polyfluoroalkyl substances, the persistent “forever chemicals.” The rule set enforceable Maximum Contaminant Levels for five individual compounds and one mixture:
- PFOA: 4.0 parts per trillion (ppt), with a health goal (MCLG) of zero
- PFOS: 4.0 ppt, MCLG zero
- PFHxS: 10 ppt
- PFNA: 10 ppt
- HFPO-DA (GenX chemicals): 10 ppt
- A Hazard Index of 1 for mixtures containing two or more of PFHxS, PFNA, HFPO-DA, and PFBS
The rule gave public water systems three years, until 2027, to complete initial monitoring, and five years, until 2029, to install treatment where limits are exceeded.
The May 2026 proposals would keep two limits and cut four
The EPA announced two proposed rules on May 18, 2026.
The first proposal upholds the standards for PFOA and PFOS — the two most-studied compounds, at 4.0 ppt each — while allowing water systems to request two additional years, to 2031, to comply.
The second, the proposed PFAS rescission rule, would rescind the drinking water regulations and the underlying regulatory determinations for PFHxS, PFNA, HFPO-DA, and the Hazard Index mixture. The proposal was published in the Federal Register on May 20, 2026, opening a public comment period.
Neither proposal has been finalized. Until a final rule is published, all six 2024 limits remain enforceable law, and systems’ monitoring obligations continue unchanged.
What the record shows so far
Nationwide occurrence data comes from the EPA’s fifth Unregulated Contaminant Monitoring Rule (UCMR5), which required large and many small systems to test for 29 PFAS compounds. Those results — not the compliance monitoring still ramping up — are the data behind most PFAS findings reported today, including the detections shown on TapGraded’s PFAS contaminant pages.
Three reading notes for anyone checking a local system:
- A detection is not an exceedance. A system can detect PFOA at 2 ppt and be under the limit. The Tap Grade methodology distinguishes the two: a result at or above an MCL carries a heavier deduction than a detection below it.
- Many systems show no PFAS data yet. Initial monitoring runs into 2027; absent data means untested or unreported, not clean.
- Local checks are faster than federal ones. TapGraded’s PFAS check tool reports whether a given utility’s testing has found PFAS, at what levels, and against which limits.
For households where PFAS has been confirmed, only specific treatment types are certified for PFAS reduction; the filter guides list which technologies have certifications that cover it.
What happens next
The comment periods on both proposals close before any final action; the EPA has not announced a date for final rules. Three outcomes are possible: the proposals are finalized as written, they are modified in response to comments, or they are withdrawn.
Until any of that happens, the operative facts are unchanged: six limits in force, monitoring due by 2027, compliance due by 2029, and a proposal on the table that would narrow the rule to PFOA and PFOS with a 2031 horizon. This page will be updated as the rules move.
Sources
- US EPA — “Per- and Polyfluoroalkyl Substances (PFAS)” — https://www.epa.gov/sdwa/and-polyfluoroalkyl-substances-pfas
- US EPA — “Proposed PFAS Rescission Rule” — May 18, 2026 — https://www.epa.gov/sdwa/proposed-pfas-rescission-rule
- Federal Register — “Rescission of Regulatory Determinations and Removal of Related Provisions for Four PFAS Substances” (proposed rule) — May 20, 2026 — https://www.federalregister.gov/documents/2026/05/20/2026-10085/rescission-of-regulatory-determinations-and-removal-of-related-provisions-for-four-pfas-substances
- US EPA — “Occurrence Data for the Unregulated Contaminant Monitoring Rule (UCMR)” — https://www.epa.gov/dwucmr/occurrence-data-unregulated-contaminant-monitoring-rule
- US EPA — “National Primary Drinking Water Regulations” — https://www.epa.gov/ground-water-and-drinking-water/national-primary-drinking-water-regulations
Source: Regulatory facts cited inline against EPA sources; see Methodology & Data sources · Data as of July 18, 2026
This article is informational and is not health, legal, or engineering advice. Questions or corrections: contact@tapgraded.com.