The U.S. Environmental Protection Agency (“EPA” or the “Agency”) is proposing a National Primary Drinking Water Regulation (NPDWR) for perchlorate and a health-based Maximum Contaminant Level Goal (MCLG) under the Safe Drinking Water Act (SDWA). In this action, the EPA is proposing to set the perchlorate MCLG at 0.02 mg/L (20 µg/L). The EPA is also proposing and taking comment on setting an enforceable Maximum Contaminant Level (MCL) for perchlorate at 0.02 mg/L (20 µg/L), 0.04 mg/L (40 µg/L), or 0.08 mg/L (80 µg/L). The EPA is also proposing requirements for water systems to conduct monitoring for perchlorate in drinking water, take mitigation actions if the level exceeds the MCL, provide information about perchlorate to their consumers through public notification and consumer confidence reports, and report to their respective primacy agency. The Administrator has determined that the benefits of this regulation would not justify the costs; however, the EPA is required to issue an NPDWR and MCLG for perchlorate in response to the D.C. Circuit’s decision in NRDC v. Regan.

DATES:

Comments must be received on or before March 9, 2026. Comments on the information collection provisions of the proposed rule under the Paperwork Reduction Act (PRA) must be received by the Office of Management and Budget’s Office of Information and Regulatory Affairs (OMB-OIRA) on or before February 5, 2026. Please refer to the PRA section under “Statutory and Executive Order Reviews” in this preamble for specific instructions. Public hearing: The EPA will hold a virtual public hearing on February 19, 2026, at https://www.epa.gov/​sdwa/​perchlorate-drinking-water. Please refer to the SUPPLEMENTARY INFORMATION section for additional information on the public hearing.

Federal Register