According to a Law360 article, U.S. EPA said in a statement to Law360 that it’s reviewing a November 2024 petition from 175 environmental groups to include microplastics in the Sixth Unregulated Contaminant Monitoring Rule (UCMR 6) under the Safe Drinking Water Act (SDWA).
The SDWA requires the EPA to create a list of up to 30 unregulated contaminants to be monitored in public water systems every five years, known as the UCMR. UCMR 6, which will cover a monitoring period from 2027-2031, is scheduled for a notice of proposed rulemaking in August 2025 and a final rule in December 2026.
The potential inclusion of microplastics in UCMR 6 would result in monitoring results being made publicly available in the National Contaminant Occurrence Database. It could also result in the potential listing of microplastics in the Contaminant Candidate List if the EPA determines that microplastics are known or anticipated to occur in public water systems and may require regulation under the SDWA. This could result in the eventual regulation of microplastics under the SDWA if the EPA determines, based on the best available public health information, that:
- microplastics have adverse human health effects;
- microplastics are known to occur or there is a substantial likelihood that they will occur in public water systems with a frequency and at levels of public health concern; and
- in the sole judgment of the EPA, regulation of microplastics presents a meaningful opportunity for health risk reduction for persons served by public water systems.
In selecting unregulated contaminants for consideration, the EPA must prioritize contaminants that present the greatest public health concern. Regulation of microplastics under the SDWA would result in a Maximum Contaminant Level (MCL) Goal and National Primary Drinking Water Regulation with an enforceable MCL for microplastics.
The petition refers to the potential health effects associated with microplastics as well as the chemical additives and contaminants they carry, as well as the alleged ubiquity and presence of microplastics in drinking water.
The petition also notes that the EPA is in the process of developing a microplastics testing methodology and points to California’s adoption of two approved microplastics testing methodologies for use in its microplastics monitoring program. As previously explained, the California Water Resources Control Board has been monitoring microplastics in drinking water pursuant to legislation passed in 2018.
The petition urges that the EPA not delay monitoring for microplastics until subsequent UCMR cycles as this would result in unnecessary delay in regulating microplastics.
Time will tell whether microplastics are added to UCMR 6 or a subsequent UCMR.
In the interim, we will continue to closely follow legal developments concerning microplastics and provide timely updates on the Corporate Environmental Lawyer.
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