Comment Letter: US EPA Revisions to Establish 6th Unregulated Contaminant Monitoring Rule for Public Water Systems Aug 31, 2026 Comment Letters Agency: United States Environmental Protection Agency Subject: U.S. Environmental Protection Agency: Revisions To Establish the Sixth Unregulated Contaminant Monitoring Rule (UCMR 6) for Public Water Systems — Docket ID No. EPA-HQ-OW-2023-0469 Letter excerpt: The Association of California Water Agencies (ACWA) respectfully submits comments regarding the U.S. Environmental Protection Agency’s (EPA) proposal for the sixth Unregulated Contaminant Monitoring Rule (UCMR 6). ACWA appreciates EPA efforts to improve water quality through science-based occurrence data frameworks like the UCMR. EPA’s UCMR 6 proposal would require public water systems to collect national occurrence data for certain PFAS, as well as organic compounds and pesticides, that may be present in drinking water but are not yet subject to federal standards under the Safe Drinking Water Act (SDWA). EPA will use the data collected through the final version of the UCMR 6 to inform its decision-making process on which contaminants to regulate under the SDWA. ACWA generally supports EPA’s proposed UCMR 6 but urges EPA to consider the following comments. Download Comment Letter
