Monitoring Microplastics: Recent Regulatory And Litigation Developments

Microplastics, plastic particles ranging in size from 5 millimeters, or about the size of a pencil eraser, to an invisible 1 nanometer,¹ continue to garner public attention. While the general public is concerned about microplastics, Environmental Protection Agency (EPA) action in Summer 2026 demonstrates that the Agency is not yet ready to prioritize federal regulation of microplastics under the Safe Drinking Water Act (SDWA). Despite the regulatory landscape, the plaintiff’s bar remains active in the microplastics space. Below, we provide a roundup of recent microplastics updates.

EPA action under the Safe Drinking Water Act

Unregulated Contaminant Monitoring Rule (UCMR)

The UCMR program under the SDWA requires public water systems to gather data for UCMR-listed contaminants that may be present in drinking water and that do not currently have health-based standards under the SDWA. The purpose of the UCMR program is to collect data that EPA can use to inform Agency decisions