Drinking Water Standards (PFAS)

Drinking water standards for PFAS set maximum contaminant levels (MCLs) or quality thresholds for PFAS compounds in public water supplies. In the U.S., EPA finalized the National Primary Drinking Water Regulation (NPDWR) in April 2024, setting individual MCLs of 4 parts per trillion (ppt) for PFOA and PFOS, and a hazard index-based limit for mixtures of PFHxS, PFNA, HFPO-DA (GenX), and PFBS. The EU Drinking Water Directive (EU) 2020/2184 sets a limit of 0.1 µg/L for 20 specified PFAS and 0.5 µg/L for total PFAS, applicable from January 2026.

EPA NPDWR for PFAS (89 FR 32532, April 2024); EU Drinking Water Directive (EU) 2020/2184, Article 13; SDWA.

Drinking water standards create upstream compliance pressure for manufacturers whose products release PFAS into the environment. Water utilities must install treatment systems (granular activated carbon, ion exchange, or high-pressure membranes) to meet these limits. Manufacturers of PFAS-containing products may face CERCLA or state-level liability for contaminating water sources that now exceed these thresholds. The stringency of 4 ppt for PFOA/PFOS (effectively near detection limits) means even trace releases can cause exceedances.

A public water system serving 50,000 people detects PFOA at 12 ppt in its treated water. Under EPA’s NPDWR, the utility must install treatment to reduce PFOA below 4 ppt. The utility then pursues cost recovery from upstream industrial dischargers under CERCLA and state environmental statutes.