The Microplastics Regulatory Clock Is Ticking

On April 6, 2026, the U.S. Environmental Protection Agency (EPA) released the draft of its sixth Contaminant Candidate List (CCL) under the Safe Drinking Water Act (SDWA), including, for the first time, microplastics as a priority contaminant group (91 Fed. Reg. 17186). This is yet another indication of how regulatory and litigation attention is increasingly focusing on microplastics. Industrial stakeholders need to be aware.

Background

SDWA Section 1412(b)(1)(B)(i) requires that EPA publish the CCL every five years. Listed contaminants are not regulated under the National Primary Drinking Water Regulations, but either occur or are likely to occur in public drinking water systems. Inclusion on the CCL indicates that the chemical or group of chemicals warrants consideration for regulation under SDWA.

This sixth iteration of the CCL contains 75 chemicals, four chemical groups, and nine microbes. The four groups are microplastics, per- and polyfluoroalkyl substances (PFAS), disinfection byproducts and pharmaceuticals. These four groups are reportedly included because EPA has identified them as priorities for evaluation due to public stakeholder input and other EPA actions. EPA will evaluate the groups and certain individual chemicals within the groups using available data.

Draft Sixth CCL and Microplastics

Importantly, EPA and the U.S. Department of Health and Human Services (HHS) released on April 2, 2026, a joint press release announcing “historic actions to protect Americans from microplastics and safeguard drinking water,” including the listing of microplastics on the draft CCL. The press release describes the CCL as a “critical tool,” noting that EPA funding priorities, research initiatives and future decision-making are often tied to it. EPA notes that one motivation behind including microplastics as a group under the draft sixth CCL is to identify data gaps and areas where further research is required for EPA to evaluate adequately the contaminant for regulation under SDWA.

The draft includes the following four data “gaps.” The first is a health-based definition, meaning EPA must identify which characteristics of microplastics are associated with human health impacts stemming from drinking water exposures. Second, detection technology is lacking, and EPA must validate analytical methods and quality controls to ensure that EPA can gather accurate data. Third, EPA must better understand if and how microplastics occurring in mixtures require different detection or analytical methods. Finally, EPA must collect data on potential sources of plastic pollution that result in the presence of microplastics in drinking water.

Microplastics Under SDWA

The CCL is the first stop a contaminant takes on the journey to SDWA regulation. Contaminants listed on the CCL will be evaluated by EPA to determine whether further regulatory action is necessary. The CCL also may influence determinations related to the Unregulated Contaminant Monitoring Rule (UCMR).

The UCMR, also promulgated pursuant to SDWA, provides an avenue for EPA to track and monitor contaminants not yet officially regulated under SDWA. Public drinking water systems collect information on these contaminants for EPA’s use. UCMR data reporting is often used to gain baseline data on emerging contaminants to determine if formal regulation and drinking water standards for those contaminants should be developed.

Bringing microplastics under the scope of the CCL indicates that EPA has interest in exploring the regulatory future of microplastics in a drinking water context, and data gathered under the UCMR would bolster EPA’s ability to evaluate the particles. These actions follow EPA discussing microplastics as a priority in its November 2024 National Strategy to Prevent Plastic Pollution.

Discussion

The SDWA regulates public drinking water systems. While private entities and stakeholders along the plastics value chain are not regulated, this development signals pending regulatory changes that all stakeholders should note. “Polluter pays” policies seek to hold upstream entities responsible for downstream pollution. This policy has appeared recently in the PFAS space under the Clean Water Act, where EPA has expressed interest in holding manufacturers and producers accountable who contribute to water contamination. As regulatory entities gain a better understanding of the sources of microplastics and detecting microplastics in environmental media, EPA and private litigants can be expected to take an interest in applying the “polluter pays” principle to microplastics contamination in drinking water and other water sources.

EPA requested comment on the contaminants included in the draft, and on the process used to develop the draft. Many are expected to respond.