The United States Environmental Protection Agency has issued a proposed rule that would establish enforceable limits for perchlorate in drinking water, following a court mandate requiring the agency to regulate the contaminant. A final rule must be issued by May 21, 2027, with compliance expected three years later. The proposal sets a Maximum Contaminant Level of 20 micrograms per liter, with alternative limits under consideration. All community and non-transient non-community water systems would be required to conduct initial monitoring, with ongoing requirements determined through a tiered “binning” approach based on sampling results.

For systems exceeding the final standard, treatment upgrades may be required, including ion exchange, biological treatment, or reverse osmosis technologies. Smaller systems could implement approved small-system compliance options, including point-of-use solutions. The rule would also trigger strict public notification requirements and expanded reporting obligations. For plumbing and mechanical contractors, this regulation signals potential future work in monitoring support, system upgrades, and treatment installations as utilities prepare to meet the 2027 deadline and beyond. Click here to read more.