The U.S. Environmental Protection Agency (EPA) on Friday released a pre-publication copy of its proposed Sixth Unregulated Contaminant Monitoring Rule (UCMR 6), which is expected to be published in the Federal Register in the coming days.
The proposed UCMR 6 would require public water systems (PWSs) to collect national occurrence data for seven ultrashort organofluorine compounds (including certain per- and polyfluoroalkyl substances (PFAS)), three pesticide metabolites, 13 semivolatile organic compounds, and seven purgeable organic compounds. All samples in UCMR 6 will be point of entry to the distribution system samples.
Neither microplastics nor any pharmaceuticals, including mifepristone, are included in proposed UCMR 6 monitoring.
The UCMR is an integral component of the Safe Drinking Water Act (SDWA) regulatory process, and water systems should prepare now to implement UCMR 6. As with UCMR 5, the proposed rule anticipates that all public water systems serving 3,300 persons or more will conduct sampling and that there will be a statistical sample of 800 smaller systems.
This sampling plan is contingent on EPA receiving adequate funding to support sample analysis for systems serving fewer than 10,001 persons, because EPA bears the UCMR 6 analytical costs for small systems and annual federal appropriations can be uncertain.
The rulemaking is more than six months behind schedule. Systems should review the rule requirements and EPA instructions carefully. UCMR 6 monitoring begins in January 2028 and is required of both wholesale and consecutive water systems. Meeting this schedule will require planning and preparation. EPA is anticipating that all pre-monitoring activities will occur in 2026 and 2027:
- All systems participating in UCMR 6 must have a Safe Drinking Water Accession and Review System (SDWARS) account and correct information on file
- Ground water representative monitoring plan submittals
- Representative entry point monitoring plan submittals
- Large systems will need to procure laboratory analysis service from an approved laboratory (Note that EPA anticipates the process to approve laboratories will begin based on the proposed rule.)
Monitoring for ultrashort PFAS (perfluoropropanesulfonic acid (PFPrS), perfluoropropanoic acid (PFPrA), perfluoroethanesulfonic acid (PFEtS), perfluoro-2-methoxyacetic acid (PFMOAA), trifluoromethanesulfonic acid (TFMS), bistriflimide (TFSI), and trifluoroacetic acid (TFA)) will employ a new method, U.S. EPA 563. Water systems will recall that 1,2,3-trichloropropane (1,2,3-TCP) was included in UCMR 3 monitoring. In UCMR 6, method modifications will reduce the method reporting limit (MRL) from 0.03 µg/L to 0.009 µg/L. The UCMR 3 reference concentration was 0.004 / 0.04 µg/L. In the proposed Contaminant Candidate List Six the health reference level was 0.0005 µg/L.
EPA will hold identical webinars on Aug. 11 and Aug. 12, to discuss this proposal. The webinars will include information about monitoring requirements, contaminant selection and rationale, drinking water analytical methods and laboratory approval process. EPA asks those interested to register for only one of the Aug. 11 or Aug. 12 webinars.
NOTE: UCMR is implemented directly by EPA. Systems may receive direction and assistance from states in those states where the state primacy agency is assisting with implementation.
AWWA recommends members review the posted data and post local results on their websites to demonstrate transparency, explain the purpose of UCMR, and properly characterize results.
In responding to inquiries, AWWA recommends that utilities:
- Acknowledge the concern all contaminants present to safe drinking water. Emphasize to media and consumers that you are committed to protecting public health.
- Point out that your utility seeks out and monitors for unregulated contaminants under UCMR 6.
- Make clear that your water meets federal and state standards for safety (clearly explaining any SDWA violations).
- Focus on how water risks are assessed and managed, using the rigorous scientific framework of the SDWA and your state (equivalents).
- Invite media and consumers to learn more about your local water quality by providing them with consumer confidence reports and other web-based information or connecting them to the appropriate utility contact.
- If possible, contact your local health department and/or a trusted academic voice to collaborate on a response.
Water systems must distribute their consumer confidence reports (water quality reports) to customers by July 1. The CCR must include:
- An explanation of unregulated contaminants and their presence in drinking water, if detected, and
- A table summarizing data on detected regulated and unregulated contaminants.
Questions can be directed to Steve Via, AWWA director of federal relations, or Greg Kail, AWWA communications director.
