On April 6, 2026, the U.S. Environmental Protection Agency (EPA) released the draft of its sixth Contaminant Candidate List (CCL) issued under the Safe Drinking Water Act (SDWA), including for the first time microplastics as a priority contaminant group. 91 Fed. Reg. 17186. Section 1412(b)(1)(B)(i) of SDWA, as amended in 1996, requires that EPA publish the CCL every five years. The contaminants on the List are not regulated under national primary drinking water regulations, but either occur or are likely to occur in public drinking water systems. Inclusion on the List 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. According to the notice, these four groups are included because EPA has identified them as priorities for evaluation, due to both public stakeholder input and other EPA action. EPA will evaluate the groups and certain individual chemicals within the groups using available data. Comments on the draft CCL are due June 5, 2026.
Draft Sixth CCL and Microplastics
On April 2, 2026, EPA and the Department of Health and Human Services (HHS) released 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,” stating that EPA funding priorities, research initiatives, and future decision-making are often tied to the CCL.
EPA notes that one motivation of 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:
- Health-based definition: EPA must identify which characteristics of microplastics are associated with human health impacts stemming from drinking water exposures.
- Detection technology: EPA must validate analytical method(s) and proper quality controls to ensure that the Agency can gather accurate and reliable data.
- Microplastics combined with other substances: EPA must better understand if and how microplastics occurring in mixtures require different detection or analytical methods.
- Sources: EPA must collect data on potential sources of plastic pollution that result in the presence of microplastics in drinking water.
The docket for the draft CCL includes studies on the presence of microplastics in human tissue, studies on quantifying human exposure to microplastics, and a public nomination to include microplastics on the List.
Microplastics under SDWA
The CCL is the first stop a contaminant takes on the journey to regulation under SDWA. Contaminants 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.
The inclusion of microplastics on the draft sixth CCL comes after a November 26, 2025, petition of seven states’ Governors to include microplastics under the next iteration of the UCMR. EPA likely has a duty to include microplastics under the rule in response to this petition, as SDWA requires EPA to include a contaminant within the UCMR if Governors from at least seven states petition for the addition (unless EPA determines this would prevent listing higher priority contaminants). EPA is currently working on drafting the next iteration of the UCMR and is expected to publish a draft for public comment in 2026.
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.
Commentary
While SDWA regulates public drinking water systems and not private entities or stakeholders along the plastics value chain, regulation under SDWA may signal pending regulatory changes that may impact stakeholders. “Polluter pays” policies seek to hold upstream entities responsible for downstream pollution. This policy has manifested recently in the PFAS space under the Clean Water Act, where EPA has expressed interest in accountability for manufacturers and producers that contribute to contamination in wastewater. As regulatory entities gain a better understanding of sources of microplastics and tracking sources of microplastics, EPA may have an interest in applying the “polluter pays” principle to microplastics contamination in drinking water and other water sources.
EPA is seeking comment on the contaminants included in the draft, and on the process used to develop the draft. EPA also seeks comments on the groups of contaminants included in the draft CCL, including microplastics. Bergeson & Campbell, P.C. recommends that stakeholders review the draft List and the SDWA regulatory framework to evaluate if submitting a comment in response to the draft CCL would be beneficial.