Earlier this month, AMWA submitted comments to EPA on its draft sixth Contaminant Candidate List (CCL 6), which represents the list of contaminants that are not currently subject to any proposed or promulgated national primary drinking water regulation. The list includes 75 chemicals, 9 microbes, and 4 chemical groups that represent tens of thousands of individual chemicals, including microplastics, pharmaceuticals, per- and polyfluoroalkyl substances (PFAS), and a list of specific microbial disinfection byproducts (MDBPs). Publication of the CCL is an important initial step in the Safe Drinking Water Act (SDWA) regulatory process, as SDWA requires EPA every five years to prioritize a list of contaminants that may occur in drinking water.
Filed with the agency on June 5, AMWA’s comments encouraged the agency to use the CCL as an opportunity to prioritize limited scientific and research resources by focusing on processes and contaminants that can most likely inform SDWA’s regulatory processes. Specifically, the association’s comments suggest EPA include for all listed contaminants and contaminant groups information about the relevant state of knowledge on adverse health impacts from drinking water exposure, occurrence in drinking water sources, and availability of drinking water analytical methods. The comments also suggest EPA include, for all of the listed contaminants and contaminant groups, a transparent ranking of EPA’s prioritization of research and potential next steps, such as monitoring under the Unregulated Contaminant Monitoring Rule (UCMR). Furthermore, the comments demonstrate that the Agency has significantly expanded the total universe of contaminants considered in the CCL universe through the inclusion of large chemical groups, obscuring which individual contaminants are priorities for the Agency’s research efforts. Finally, in response to EPA’s two new chemical group listings, AMWA’s comments discussed the numerous data gaps related to microplastics and argued that the listing of pharmaceuticals as a class is too broad to help the Agency or public focus concerted research efforts.
AMWA’s comments follow its regular monitoring of the CCL process. On January 15, 2025, EPA released preliminary determinations not to regulate the nine contaminants, to which AMWA responded. The contaminants included on the fifth CCL for which EPA is not making a regulatory determination are under consideration for inclusion in the forthcoming draft Sixth CCL, to which AMWA also responded in 2023. The draft CCL 6 will help prioritize funding, research, and information-collection to better understand the potential risks of these substances in drinking water while advancing the agency’s commitment to gold standard science.
Each CCL serves as a primary resource for selecting contaminants for each 5-year Unregulated Contaminant Monitoring Rule (UCMR) monitoring cycle, which EPA should soon release for public review and comment. According to the Office of Information and Regulatory Affairs (OIRA), which conducts interagency review of Agency regulations, EPA sent the draft UCMR 6 to OIRA for review on March 27. The sixth UCMR will have a five-year period of 2027-2031. Under the rule, water systems would make monitoring preparations in 2027, with sample collection between 2028 through 2030 and reporting concluding in 2031.