For two years, plaintiff-side lawyers worked under an assumption: federal regulation of PFAS in drinking water would create a relatively uniform liability framework. The 2024 EPA rule set Maximum Contaminant Levels for six PFAS chemicals — including PFOA and PFOS at 4 parts per trillion, and 10 ppt each for PFHxS, PFNA, and GenX (HFPO-DA), plus a novel Hazard Index for mixtures — and gave water systems until 2029 to comply with those MCLs and 2027 to meet monitoring requirements. That rule looked like a foundation. Federal limits become the implicit yardstick for what counts as contamination, and contamination is what plaintiffs sue over.

That assumption has collapsed.

In May 2025, EPA Administrator Lee Zeldin announced the agency would keep the PFOA and PFOS standards but proposed extending compliance to 2031 and establishing a federal exemption framework. Separately, EPA announced its intent to rescind the regulations and reconsider the regulatory determinations for PFHxS, PFNA, HFPO-DA, and the Hazard Index mixture. The agency is now in active rulemaking to formalize the rollback. The D.C. Circuit denied EPA's request to summarily vacate four of the Biden-era rules in January 2026, finding the merits not so clear as to warrant summary action, and in March 2026 denied the agency's request to sever and hold those challenges in abeyance.

The federal floor is moving, but it isn't gone — and the litigation around what it should be is very much alive.

What this changes for plaintiff lawyers isn't whether PFAS cases proceed. It's where the regulatory anchor sits.

The state floor is now higher than the federal floor

California is the cleanest example. The Division of Drinking Water set notification levels of 4 ppt for PFOA and PFOS, 3 ppt for PFHxS, and 1,000 ppt for PFHxA, with response levels at 10 ppt for PFOA and PFHxS, 40 ppt for PFOS, and 10,000 ppt for PFHxA. These are not enforceable MCLs, but exceedances trigger immediate requirements for notification, public disclosure, and consideration of operational responses, including removing a water source from service. They function as evidentiary standards in a different sense: they establish what the state considers actionable contamination, what water systems are expected to disclose, and what counts as a known risk. For plaintiffs alleging exposure-based injury, "the State of California flagged this as actionable at 3 parts per trillion" is a more usable fact than it was a year ago.

California is not alone. Connecticut, Vermont, and Maine have moved on PFAS labeling laws and product bans. New York is regulating biosolid wastes. Regulatory attorneys describe a pattern in which states have picked up on the sense that the federal government has retreated from limiting and restricting PFAS, and have rushed to fill what they perceive as a void. The expectation in the industry is that every state, if it has not already, will enact reporting obligations or product restrictions on PFAS. State-level disclosure obligations aren't contracting; they're expanding into product categories — textiles, cookware, cosmetics, food packaging — that haven't traditionally been part of PFAS exposure cases.

What this looks like in litigation

Three implications worth thinking about.

First, venue selection becomes more consequential. A PFAS personal-injury or property-damage case anchored in California can rely on state regulatory levels stricter than what federal law now requires. A case anchored in a state without independent PFAS regulation has to do more evidentiary work to establish what counts as elevated exposure. This is not a new dynamic in toxic-tort practice, but the gap between strict-regulation states and the federal baseline is widening, and that gap is now the question.

Second, the universe of potential defendants is shifting away from a narrow set of manufacturers. The 2024 designation of PFOA and PFOS as CERCLA hazardous substances created liability exposure for water utilities, waste haulers, landfills, and industrial users. Trade associations representing water utilities are now pressing Congress for "passive receiver" exemptions, arguing that ratepayer funding will be diverted from infrastructure to litigation costs if utilities are treated as potentially responsible parties under CERCLA. Environmental groups are pushing the opposite direction, urging stricter PFAS enforcement. Whichever way that lands, the next phase of PFAS litigation will involve more defendants, more cross-claims, and more allocation fights than the early-wave aqueous film-forming foam cases did.

Third, the regulatory rollback creates an evidentiary asymmetry plaintiff lawyers should be ready to exploit. EPA went on record in 2024 that PFHxS, PFNA, GenX, and PFBS at low levels in drinking water present unreasonable risk. The 2026 rulemaking to rescind those determinations argues the agency's process was procedurally inadequate, not that the underlying science was wrong. The 2024 administrative record — the technical support documents, the response to public comments, the cost-benefit analyses — doesn't disappear because the rule does. Defense counsel will argue the rollback proves these chemicals weren't really regulated. The 2024 record says otherwise, and that record is citable.

The takeaway

Federal contraction does not make PFAS litigation easier or harder in the aggregate. It makes it more state-dependent, more defendant-fragmented, and more dependent on regulatory record-building rather than regulatory citation. Lawyers who treated the 2024 NPDWR as the answer to their causation framework now have to rebuild it using state notification levels, the underlying federal administrative record, and emerging product-category regulations across multiple jurisdictions.

The work didn't get smaller. It got more specific.