EPA Declines To Require Microplastics Monitoring Under Its Proposed UCMR 6

On July 1, 2026, the U.S. Environmental Protection Agency (EPA) published its proposed Sixth Unregulated Contaminant Monitoring Rule (UCMR 6) that — despite years of pressure from states and advocacy groups — does not include microplastics. Under the Safe Drinking Water Act (SDWA), the UCMR is the mechanism EPA uses to require public water systems to monitor for unregulated contaminants and generate nationwide occurrence data that informs whether a contaminant should later be regulated. The proposed UCMR 6 would require monitoring for certain PFAS and other organofluorine compounds, several pesticide metabolites, and a range of semivolatile and purgeable organic compounds. Microplastics, which EPA included earlier this year on its draft Contaminant Candidate List 6 (CCL 6), were absent from the list — an issue EPA expressly addressed in the UCMR proposal.