Under the 1996 amendments to the federal Safe Drinking Water Act, the U.S. Environmental Protection Agency is required once every five years to issue a new list of up to 30 unregulated contaminants for which public water systems must monitor. The intent of this rule is to provide baseline occurrence data that the EPA can combine with toxicological research to make decisions about potential future drinking water regulations.
The most recent UCMR, the Fifth Unregulated Contaminant Monitoring Rule
(UCMR5), will be signed by EPA Administrator Michael Regan in Dec. 2021. The EPA, the states, laboratories and public water systems will participate in the testing for UCMR 6 in various ways. The testing occurs between January 2023 and December 2025.