On Friday, June 26, EPA announced the release of its draft sixth Unregulated Contaminant Monitoring Rule (UCMR 6). SDWA requires EPA to issue a list of up to 30 unregulated contaminants to be monitored by public water systems every five years, and the next cycle, UCMR 6, will occur from 2027-2031.
EPA selects contaminants for the UCMR based on factors such as known or anticipated occurrence in drinking water sources, available public health information, and practical considerations, including sampling methods, laboratory availability, and cost. The draft UCMR 6 includes 30 contaminants, including some legacy solvents, certain pesticides, chemical intermediaries from combustion, and certain ultrashort-chain PFAS.
Under the rule, water systems would make monitoring preparations in 2027, with sample collection between 2028 through 2030 and reporting concluding in 2031. AMWA will work with the regulatory subcommittee to review and develop comments in response to the draft UCMR 6 when it is published in the Federal Register.
The UCMR 6 comes on the tail of the draft Sixth Candidate Contaminant List, to which AMWA responded earlier this spring. Each CCL serves as a primary resource for selecting contaminants for each 5-year Unregulated Contaminant Monitoring Rule (UCMR) monitoring cycle.
According to the press release, the proposed UCMR 6 Rule will be available for a 60-day public comment period. During that time, the agency will host two identical public webinars on August 11, 2026, and August 12, 2026. Individuals interested should register for the webinars online. Interested individuals may also visit EPA’s UCMR website for more information on past UCMR cycles.
EPA's latest Regulatory Agenda had planned to finalize a proposal for the sixth UCMR by December 2025. In November 2024, 175 groups sent a petition to EPA to include microplastics in UCMR6, and microplastics were a new addition to the draft CCL 6. AMWA, along with numerous other organizations, identified the lack of established scientific consensus on the health effects of specific sizes and polymers of microplastics, as well as lack of standardized sampling and analytical methods in CCL 6 comments.