UCMR 6: EPA Sidesteps Microplastics, For Now

Summary

On July 1, 2026, EPA proposed the sixth Unregulated Contaminant Monitoring Rule (UCMR 6), which will require public water systems (PWS) to monitor 30 unregulated contaminants — including certain PFAS chemicals — but not microplastics. For now, EPA is using other tools, such as the Contaminant Candidate List (CCL), to learn more about microplastics before requiring PWSs to monitor for them.

UCMR 6

What UCMR 6 Would Require

Under the Safe Drinking Water Act (SDWA), Congress established a multi-step, risk-based approach for determining which contaminants would become subject to drinking water standards. Step one is the CCL, a list of contaminants not subject to any proposed or promulgated drinking water standards, that are known or anticipated to occur in PWS and may require future action under SDWA. Step two is the UCMR program, which mandates monitoring every five years of a subset of unregulated contaminants on the CCL to determine their frequency and level of occurrence