The U.S. Environmental Protection Agency (EPA) announced on January 2, 2026, the proposal of a National Primary Drinking Water Regulation (NPDWR) for perchlorate, following a 2023 court decision.
The proposed regulation includes a Maximum Contaminant Level Goal (MCLG) of 0.02 mg/L (20 µg/L) and proposes enforceable Maximum Contaminant Levels (MCLs) for perchlorate at 20 µg/L, 40 µg/L, or 80 µg/L.
Perchlorate is a chemical commonly used in products such as rocket propellants, fireworks, and airbag initiators. It can also occur naturally, particularly in arid regions of the U.S., and may be present in drinking water through contamination from certain water treatment processes or fertilizers.
This proposal follows the decision in the case NRDC v. Regan, where the D.C. Circuit court ruled that the EPA must proceed with regulating perchlorate in drinking water after the agency had withdrawn a previous determination in 2020. The EPA is now seeking public input on the proposed rule, with comments being accepted until March 9, 2026. A public hearing will also be held on February 19, 2026, from 1:00 PM to 4:00 PM ET, where individuals can provide verbal comments.
The EPA noted a reduction in perchlorate levels in drinking water since the agency began evaluating the chemical for regulation in 2011. If finalized, the regulation could affect water systems across the country and potentially improve public health by addressing the risks associated with perchlorate contamination.
As part of the process, the EPA is providing additional resources, including recommendations for public water systems to manage perchlorate levels and guidelines for treatment technologies.
