Revisions to Establish the Sixth Unregulated Contaminant Monitoring Rule (UCMR 6) for Public Water Systems

The Safe Drinking Water Act (SDWA), as amended in 1996, requires that the EPA establish a program to monitor up to 30 unregulated contaminants every five years. EPA published the rule defining the fifth cycle of monitoring (UCMR 5) on December 27, 2021 (86 FR 73131). This action meets the SDWA requirement by establishing the terms for the next (sixth) cycle of monitoring and identifying the new unregulated contaminants to be monitored during the five-year UCMR 6 period of 2027-2031. Monitoring preparations are anticipated in 2027, with sample collection between 2028-2030 and reporting concluding in 2031. Related Docket: EPA-HQ-OW-2020-0530