Upcoming Drinking Water Regulation Changes: 2026–2029
How to read this guide
Regulatory news is noisy. This guide uses three labels, strictly:
- FINAL — published in the Federal Register as a final rule, or a court order with legal effect. This is the law.
- PROPOSED — an NPRM or announced intent. It signals direction but changes nothing until finalized.
- IN LITIGATION — a final rule under court challenge. It remains in force unless a court stays or vacates it.
A note on sources. Limits and dates below trace to the Code of Federal Regulations and the Federal Register — the primary sources. EPA web pages and fact sheets are useful for timelines and implementation detail, but they are derivative: when a fact sheet and the rule disagree, the rule wins. That is why this site cites CFR first.
PFAS: two tracks running at once
Track 1 — The federal CFR track 2024 FINAL 2026 PROPOSALS PENDING
The April 2024 PFAS National Primary Drinking Water Regulation (89 FR 32532) set enforceable MCLs for six PFAS — PFOA and PFOS at 4.0 ppt each; PFHxS, PFNA, and HFPO-DA (GenX) at 10 ppt each; and a Hazard Index of 1.0 (unitless) for mixtures including PFBS. Initial monitoring must be complete by 2027, with MCL compliance from 2029. That rule is in force today.
In May 2026 EPA issued two proposals: (1) rescind the PFHxS/PFNA/HFPO-DA/Hazard-Index standards and re-evaluate them (NPRM May 20, 2026, 91 FR 29413, docket EPA-HQ-OW-2025-0654; public hearing July 7, 2026; comments closed July 20, 2026); and (2) extend the PFOA/PFOS MCL compliance date from April 26, 2029 to April 26, 2031 for eligible systems. As of late August 2026, EPA had issued no final rule on either proposal — the agency says it intends final action during 2026, but until then the 2024 rule stands as written, including the 2029 date.
Separately, an August 11, 2026 EPA Office of Water memo withdrew Clean Water Act guidance that directed states to keep PFAS out of source water via discharge permits. That withdrawal changes no drinking-water MCL — but it shifts more of the cleanup burden downstream, to treatment at the drinking-water plant.
Track 2 — The DoD/Navy policy track POLICY IN FORCE
Department of Defense installations follow DoD PFAS drinking-water policy alongside (and sometimes ahead of) the CFR:
- March 11, 2026 (CNIC 5090 Ser N4/26U020): Navy-wide implementation of the two policies below — initial monitoring by April 26, 2027 at all entry points to the distribution system (EPA Method 533; frequencies by system size and source type), ongoing compliance monitoring from April 26, 2027, MCL compliance by April 26, 2029, plus 30-day public webpage posting, Consumer Confidence Report, and Tier 2/Tier 3 public-notification requirements.
- September 28, 2025 (ASD EI&E): OCONUS policy — overseas installations complete PFAS monitoring by April 26, 2027.
- December 4, 2024: DoD policy for domestic DoD-owned drinking-water systems aligning with the federal PFAS rule.
- 2023 DoD monitoring policy: PFAS monitoring at all DoD-owned and operated water systems at least every two years; if PFOA/PFOS exceed the 2016 EPA health advisory of 70 ppt (individual or combined), systems must provide alternative water and correct the exceedance.
If you consult for a Navy or other DoD installation, the installation’s Final Governing Standards may incorporate these policies — check the FGS, not just the CFR. (DoD PFAS policies are posted on the DoD PFAS Task Force policy page.)
Lead and copper: LCRI countdown with a lawsuit in the background
The Lead and Copper Rule Improvements (final rule, October 2024) are the biggest lead-rule rewrite in 30 years: the lead action level drops to 0.010 mg/L (10 ppb), tap sampling changes (first- and fifth-liter draws), every system needs a service-line inventory, and lead service lines must be replaced within 10 years. COMPLIANCE BEGINS NOV 1, 2027
The American Water Works Association sued (AWWA v. EPA, D.C. Circuit, filed December 2024), challenging mainly the requirement to replace private-side service lines the utility can “access” but does not own. Oral argument was held September 30, 2026 — and notably, the current EPA defended the rule in court. NO STAY ISSUED — the November 2027 date and all requirements stand unless the court says otherwise.
Perchlorate: the next new MCL
After a D.C. Circuit decision (NRDC v. Regan, May 2023) vacated EPA’s withdrawal of its determination to regulate, a consent decree ordered EPA to propose by January 2, 2026 and finalize by May 21, 2027. PROPOSED JAN 2026
- Proposal: MCLG of 0.02 mg/L (20 µg/L); enforceable MCL co-proposed at 20, 40, or 80 µg/L (91 FR 398, January 6, 2026; docket EPA-HQ-OW-2024-0592; comments closed March 9, 2026).
- Scope if finalized: ~66,000 community and non-transient non-community systems monitor; initial monitoring complete within 3 years of the final rule; mitigation, public notice, and state reporting for exceedances.
- Why it matters now: perchlorate (rocket propellant, munitions, fireworks; also naturally occurring in the Southwest) would become the first new inorganic MCL in decades — a template for how future contaminants get regulated.
Timeline: dates that matter
| When | What | Status |
|---|---|---|
| 2026 (intended) | EPA final action on PFAS rescission + PFOA/PFOS 2031 extension | PROPOSED |
| April 26, 2027 | PFAS initial monitoring complete (2024 rule); OCONUS DoD PFAS monitoring complete | FINAL / POLICY |
| May 21, 2027 | Perchlorate final rule due (consent decree) | PROPOSED |
| November 1, 2027 | LCRI compliance begins: 10 ppb lead AL, inventories, replacement clock starts | FINAL LITIGATION |
| April 26, 2029 | PFOA/PFOS MCL compliance (2031 if extension finalized) | FINAL |
| 2037 | Lead service line replacement complete (10-year LCRI clock) | FINAL |
What your system should do now
- Do not plan around proposals. Budget and schedule against final rules; track proposals separately.
- Calendar the 2027 dates: PFAS initial monitoring, LCRI compliance, perchlorate final rule.
- If you have lead service lines, the inventory and replacement planning start now — not in 2027.
- DoD/Navy systems: confirm which PFAS policy your FGS incorporates and the April 2027 OCONUS monitoring deadline.
- Re-check this page and the Compliance Center monthly — the PFAS final rules could land any time.
Related
- Drinking Water Compliance Center — every federal limit, searchable
- PFAS Drinking Water Rules: What’s Final, What’s Proposed
- LCRI Explained
- Compliance Monitoring Planner — build the schedule around these dates
Sources
- PFAS NPDWR final rule, 89 FR 32532 (April 2024) — six PFAS MCLs.
- PFAS rescission NPRM, 91 FR 29413 (May 20, 2026), docket EPA-HQ-OW-2025-0654, RIN 2040-AG53; hearing July 7, 2026; comments closed July 20, 2026. Status as of Aug 2026: no final rule — WaterVerge docket tracker.
- EPA Office of Water memo withdrawing CWA PFAS source-water guidance, August 11, 2026 (reported Sept 2026).
- LCRI final rule, October 2024 — 0.010 mg/L lead AL, Nov 1, 2027 compliance, 10-year replacement.
- AWWA v. EPA, D.C. Circuit — oral argument Sept 30, 2026 (“control” over private-side service lines); no stay — Bloomberg Law; WaterVerge.
- Perchlorate NPRM, 91 FR 398 (Jan 6, 2026), docket EPA-HQ-OW-2024-0592; MCLG 0.02 mg/L; MCL options 20/40/80 µg/L — EPA perchlorate page; EPA FAQ.
- NRDC v. Regan, D.C. Circuit (May 2023); consent decree deadlines: proposal Jan 2, 2026, final rule May 21, 2027.
- DoD PFAS drinking-water policies: 2023 monitoring policy; Dec 4, 2024 domestic policy; Sept 28, 2025 OCONUS policy (ASD EI&E) — DoD PFAS Task Force policies; CNIC 5090 Ser N4/26U020 (Mar 11, 2026), Navy implementation of the Dec 2024/Sept 2025 policies.