On October 29, 2025, California’s State Water Resources Control Board, Division of Drinking Water (“DDW”) announced the issuance of updated notification and response levels for several PFAS in drinking water, including PFOA, PFOS, PFHxS, and PFHxA.  The revised guidance establishes new, health-based advisory thresholds. 

The new advisory levels lower thresholds for several compounds and expand the scope of state oversight beyond PFOA and PFOS.  Specifically, the DDW set notification levels of 4 parts per trillion (“ppt”) for PFOA and PFOS, 3 ppt for PFHxS, and 1,000 ppt for PFHxA.  Response levels were set at 10 ppt for PFOA and PFHxS, 40 ppt for PFOS, and 10,000 ppt for PFHxA.  Although these thresholds are not enforceable maximum contaminant levels (“MCLs”) with respect to the amount of these PFAS allowed in drinking water, exceedances trigger immediate requirements for notification, public disclosure, and consideration of operational responses, such as removing a water source from service.

For water providers and regulated industries, the revised levels heighten compliance and litigation exposure.  The DDW’s announcement underscores California’s precautionary approach to PFAS management and signals that formal, enforceable limits may follow, especially as EPA prepares to revisit certain parts of its 2024 rulemaking in 2026.