On 20 May 2026 the US Environmental Protection Agency (EPA) proposed a federal exemption rule under sections 1416(f) and 1450(a)(1) of the Safe Drinking Water Act. The rule would extend the compliance deadline for the maximum contaminant levels (MCLs) for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) in public water systems by two years, from 26 April 2029 to 26 April 2031.

Why the extension

PFOA and PFOS are "forever chemicals" that degrade extremely slowly in the environment and the human body. The EPA set strict MCLs for both in 2024, at 4.0 ppt each, and required compliance by April 2029. Many water systems, however — particularly small and rural communities — face practical difficulties with technical assessment, equipment procurement (such as granular activated carbon filtration or reverse osmosis systems), financing and staff training. The extension is intended to avoid penalising systems under a one-size-fits-all deadline while concentrating resources on actually reducing contaminant concentrations.

Key points of the rule

Standards unchanged: the MCL values remain at 4.0 ppt; only the compliance deadline is extended.

Scope: the rule is expected to affect about 66,000 public water systems across the United States. Systems that are eligible and apply may obtain an exemption.

Cost savings: the proposal could save small water systems serving fewer than 10,000 people roughly USD 15.7 million to USD 32.2 million a year.

Public participation

Comments close on 20 July 2026 and may be submitted through the federal regulations website (www.regulations.gov) under docket number EPA-HQ-OW-2025-1742.

A public hearing will be held online on 7 July 2026. Those wishing to speak must register by 1 July 2026.

The EPA said it will publish a final rule during the year after considering public comments.