PFAS Rule Faces Court Test as Uncertainty Grows

A court battle over EPA PFAS limits leaves US water utilities unsure how to plan costly upgrades or meet shifting deadlines

23 Jan 2026

The future of the US Environmental Protection Agency’s drinking water limits for per- and polyfluoroalkyl substances (PFAS) now rests on federal court proceedings, leaving public water systems uncertain over compliance and investment plans.

In January, the US Court of Appeals for the District of Columbia Circuit rejected the EPA’s request to immediately vacate four of the six PFAS standards. The court said the case required fuller consideration and scheduled it for a merits review. Final briefing concluded in early March, with a ruling not expected before the second half of 2026.

The dispute follows a series of regulatory changes. In May 2025, the EPA confirmed it would keep limits for PFOA and PFOS, two widely studied PFAS chemicals, at four parts per trillion. At the same time, it proposed scrapping limits for four other compounds, including GenX and PFHxS, and extending the compliance deadline for PFOA and PFOS from 2029 to 2031, citing operational challenges for utilities.

In February 2026, the agency asked the court to pause litigation on the remaining PFAS index standards while it prepares a new rulemaking to rescind them.

Utility groups, including the American Water Works Association and the Association of Metropolitan Water Agencies, have urged the court not to fully strike down the rule. In a February filing, they asked for a remand without vacatur, arguing that overturning the standards would disrupt ongoing compliance efforts.

Many utilities have already begun pilot testing and financing treatment systems such as granular activated carbon and ion exchange. Industry groups warn that a full repeal could lead to stranded investments and complicate access to state revolving fund financing.

The court’s eventual decision is expected to shape whether utilities proceed with existing multi-year capital programmes or await a revised, narrower rule from the EPA. For water providers, regulatory clarity remains a central concern alongside the technical and financial demands of PFAS removal.