EPA floats major changes to current PFAS drinking water rules

The Environmental Protection Agency (EPA) has released two proposed rules that, if finalized, would have major impacts on drinking water regulations for per- and polyfluoroalkyl substances (PFAS), specifically, the 2024 National Primary Drinking Water Regulation (NPDWR) for PFAS (2024 PFAS NPDWR).

Proposed rule: MCL compliance extension

The first rule proposes to establish a federal exemption that allows public water systems (PWSs) to request an extension of the deadline to comply with the Maximum Contaminant Levels (MCLs) for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) from April 26, 2029, to April 26, 2031.

The rule would require PWSs that meet the eligibility requirements to submit a request to EPA for the federal exemption within 180 days of the date a final rule is published. PWSs would have to provide specific information in the request (such as recent water sample results and a certified statement that the system can’t comply with the original MCL deadline).

Additionally, EPA’s proposed rule would require:

• All PWSs with the federal exemption to notify customers of the exemption, and
• PWSs with PFOA or PFOS levels at or above 12 parts per trillion to implement two control measures (from six options) during the exemption period.

Who would be impacted?

The proposed federal exemption would apply to PWSs:

• Regulated by the 2024 PFAS NPDWR for PFOA and PFOS;
• In operation on or before June 25, 2024;
• Not under a variance for small systems for the PFOA and PFOS MCLs; and
• In a state that doesn’t have primacy for the 2024 PFAS NPDWR.

PWSs in states with primacy for the 2024 PFAS NPDWR may request an exemption from the primacy agency.

Proposed rule: Rescinding PFAS NPDWRs

The second rule proposes to rescind EPA’s determinations to regulate:

• Perfluorohexane sulfonic acid (PFHxS);
• Perfluorononanoic acid (PFNA);
• Hexafluoropropylene oxide dimer acid and its ammonium salt (HFPO-DA, called GenX chemicals); and
• Perfluorobutane sulfonic acid (PFBS).

It also proposes to remove the related 2024 PFAS NPDWR provisions from 40 CFR Parts 141 and 142, including:

• The MCLs and MCL Goals (MCLGs) for PFHxS, PFNA, and HFPO-DA;
• The MCL and MCLG for mixtures with two or more of PFHxS, PFNA, HFPO-DA, and PFBS (referred to as the Index PFAS); and
• All other compliance requirements.

The proposed rule would maintain the 2024 PFAS NPDWR requirements for PFOA and PFOS.

Who would be impacted?

The rule would impact PWSs, including community water systems (CWSs) and non-transient non-CWSs, subject to the 2024 PFAS NPDWR standards for PFHxS, PFNA, HFPO-DA, or the Index PFAS.

How do I give feedback?

EPA will hold a virtual public hearing for verbal comments on the proposed rules on July 7, 2026. Written comments for the proposed compliance extension rule (Docket ID No. EPA-HQ-OW-2025-1742) and proposed rescission rule (Docket ID No. EPA-HQ-OW-2025-0654) are due by July 20, 2026.

Key to remember: EPA has proposed major changes to the national drinking water regulations for PFAS.