⚖ Oral Arguments, with Context

The D.C. Circuit hears American Water Works Association v. EPA, consolidated with challenges brought by industry groups and Chemours. PFAS are persistent synthetic chemicals found in consumer and industrial products, and exposure to some PFAS is linked to serious health effects. In 2024, EPA issued nationwide drinking-water limits for six PFAS: individual limits for PFOA, PFOS, PFHxS, PFNA, and HFPO-DA, plus a hazard-index limit for mixtures that can include PFBS. Water utilities and manufacturers petitioned for review, challenging EPA’s rulemaking sequence, occurrence data, health analysis, feasibility, and cost-benefit analysis. EPA later agreed that it had improperly combined the regulatory-determination and rulemaking steps for the index PFAS, stopped defending those provisions, and proposed rescinding them. The court declined an early partial vacatur, leaving the merits for this argument. The first part concerns those index-PFAS provisions and whether the procedural error caused prejudice. After a recess, the court turns to whether EPA lawfully analyzed PFOA and PFOS together.

American Water Works Association v. EPA (No. 24-1188) — U.S. Court of Appeals for the D.C. Circuit, argued September 18, 2026.