On Jan. 6, 2026, EPA proposed a rule under the Safe Drinking Water Act (SDWA) that would set a Maximum Contaminant Level Goal (MCLG) of 0.02 milligrams per liter (mg/L) for perchlorate. There is no currently existing MCLG or Maximum Contaminant Level (MCL) for perchlorate, so EPA also proposed an MCL of 0.02 mg/L, 0.04 mg/L, or 0.08 mg/L. Additionally, EPA proposed requirements for water systems to: monitor perchlorate in drinking water, take mitigation actions if perchlorate levels exceed the MCL, and provide information about perchlorate to their consumers through public notification and consumer confidence reports.
Perchlorate is found in rocket fuel, explosives, matches, and airbags and can interfere with the thyroid gland, affecting hormone production. EPA determined that the benefits of regulation were not worth the costs but is taking involuntary action due to a court order resulting from the D.C. Circuit’s decision in NRDC v. Regan, 67 F.4th 397 (D.C. Cir. 2023). Public comments must be submitted by March 9, 2026.