Unregulated Contaminant Monitoring Rule (UCMR)

The Safe Drinking Water Act (SDWA) requires that once every five years the United States Environmental Protection Agency (EPA) issue a list of unregulated contaminants to be monitored by public water systems (PWSs). Since 2001, there have been five UCMRs.

• UCMR 5 (2022-2026)
• UCMR 4 (2017-2021)
• UCMR 3 (2012-2016)
• UCMR 2 (2007-2011)
• UCMR 1 (2001-2005)

The fifth Unregulated Contaminant Monitoring Rule (UCMR 5) was published on December 27, 2021 and required sample collection to analyze for 30 chemical contaminants between 2023 and 2025 using analytical methods developed by EPA and consensus organizations.

UCMR5 Monitoring in California

Findings and Summary Table: In Progress