EPA Excludes Microplastics and Pharmaceuticals from Drinking Water Monitoring

Data collected under the UCMR informs EPA actions related to the Safe Drinking Water Act (SDWA) and other risk management decisions for drinking water contaminants. Importantly, the proposed UCMR 6 does not include microplastics and pharmaceuticals, despite recent comments by EPA acknowledging their importance relative to drinking water. 

What Is the UCMR?

Each Unregulated Contaminant Monitoring Rule establishes a temporary, mandatory testing program under SWDA that requires public water systems across the country to collect data on specific parameters not yet subject to federal drinking water standards. Updated every five years, each UCMR identifies up to 30 parameters that utilities must monitor, generating the national occurrence data that EPA relies on to decide whether a substance poses a sufficient risk to justify regulation. 

The proposed UCMR 6 would cover monitoring between 2028 and 2030 and includes several per- and polyfluoroalkyl substances (PFAS), pesticide metabolites, and other organic compounds. EPA selects UCMR contaminants through a “multi-step prioritization process,” which involves identifying contaminants that “(1) were not monitored under prior UCMR cycles, (2) may occur in drinking water, and (3) are expected to have a completed, validated drinking water method in time for rule proposal.” Then EPA will consider other factors, such as health-effects information and public interest, to determine whether a contaminant should be included on the UCMR.

EPA’s Exclusion of Microplastics and Pharmaceuticals 

Despite significant stakeholder interest, EPA cites a lack of validated testing methods as its basis to exclude microplastics from UCMR 6. In other words, if microplastics were listed, water systems would simply be unable to conduct the required monitoring. EPA acknowledges the interest in microplastics monitoring and emphasized that “including these contaminants on the draft [Contaminant Candidate List] 6 … will prioritize the research that is needed to define and better understand the characteristics of microplastics.” This research may later inform the development of standardized analytical tools.

With respect to pharmaceuticals, proposed UCMR 6 similarly acknowledged the stakeholder interest in monitoring drinking water for pharmaceuticals. The proposal notes that pharmaceuticals have “been a public health concern for over a decade,” and EPA states that it is prioritizing “research and information needed to identify which pharmaceuticals are occurring in drinking water and may be of greatest public concern.” Although EPA has not provided a timeline for when pharmaceuticals might be included in a future UCMR, EPA states that placing pharmaceuticals on the Contaminant Candidate List helps prioritize identifying specific pharmaceutical parameters and the development of analytical monitoring methods.

Comments to the proposed rule are due by August 31.