Follow-Up: Multi-State Coalition Expands Support for Microplastics Regulation, Urging USEPA to Include Microplastics in Both CCL 6 and UCMR 6

As discussed in our prior microplastics client alert, in November 2025, the governors of seven states, including New Jersey, jointly petitioned (the Petition) the U.S. Environmental Protection Agency (USEPA) to include microplastics in the agency’s Sixth Unregulated Contaminant Monitoring Rule (UCMR) for drinking water.¹ The Petition was anchored in the SDWA, which requires USEPA to include in the UCMR any contaminant recommended by at least seven governors unless USEPA determines that doing so would prevent the listing of contaminants of higher public health concern.

Since the publication of that alert, two significant developments have occurred. First, on April 6, USEPA published its draft Contaminant Candidate List (CCL) 6, which includes microplastics as a chemical group.^2,3 Second, on June 5, attorneys general from 15 states and the District of Columbia, led by New Jersey Attorney General Jennifer Davenport, jointly submitted comments on the draft CCL 6 (Comment Letter), commending USEPA for including microplastics while urging the agency to go further and include microplastics in UCMR 6.⁴

A CCL is the first step in evaluating whether unregulated contaminants in drinking water warrant regulation under the SDWA.⁵ If adopted, data collected as a result of CCL 6 will assist USEPA in gaining a better understanding of the potential health risks of microplastics in drinking water.⁶ This is important because there is currently significant debate around the toxicity of microplastics. USEPA will consider proposing further microplastics regulation should the data show that (1) microplastics have an adverse effect on public health; (2) microplastics are known to occur, or there is a substantial likelihood that microplastics will occur, in public water systems with a frequency and at levels that are cause for public health concern; and (3) regulation of microplastics presents a meaningful opportunity to reduce health risks for those served by public water systems.⁷

As the attorneys general assert in the Comment Letter, while including microplastics in CCL 6 is a positive step toward understanding the impact of microplastics on public health, USEPA should “go one step further by including microplastics in the UCMR 6.”⁸ As highlighted by the attorneys general, a CCL does not impose any requirements on public water systems, whereas the UCMR would expressly require certain public water systems to monitor for the listed contaminants (in this case, microplastics) and publish results in the National Contaminant Occurrence Database, which is accessible by the public.⁹ In the event that USEPA declines to add microplastics to UCMR 6, the Petition, cited in the Comment Letter, makes clear that the 15 individual states and the District of Columbia may be forced to take independent regulatory action to address microplastics at the state level.

The regulated community is advised to closely monitor the finalization of CCL 6, which is expected by the end of November 2026, as well as the publication of UCMR 6, which is expected by the end of 2026. Given the growing multistate microplastics coalition, calls for action from environmental groups, and the evolving body of toxicity research, the comprehensive regulation of microplastics in drinking water appears increasingly likely—whether at the federal or state level. If regulation ultimately occurs at the state level (as it initially did with per- and polyfluoroalkyl substances (PFAS)), there is the risk of differing regulatory standards that must be closely monitored.

For more information on microplastics, CCL 6, and UCMR 6, please contact the authors of this client alert.

¹ The UCMR, mandated by the federal Safe Drinking Water Act (SDWA), contains a list of unregulated contaminants that must be monitored by certain public water systems. 42 U.S.C. § 300j-4(a)(2)(A)-(B).

² As required by the SDWA, USEPA must publish the CCL every five years to include unregulated contaminants that are known or anticipated to occur in public water systems and that may require regulation.  42 U.S.C. § 300g-1(b)(1)(B)(i).

³ Draft CCL 6 – https://www.federalregister.gov/documents/2026/04/06/2026-06662/drinking-water-contaminant-candidate-list-6-draft.

⁴ https://www.njoag.gov/wp-content/uploads/2026/06/2026-0605_CCL-6-Letter-6.5.26-final.pdf.

⁵ See Draft CCL 6 – https://www.federalregister.gov/documents/2026/04/06/2026-06662/drinking-water-contaminant-candidate-list-6-draft.

⁶ https://www.epa.gov/newsreleases/epa-takes-bold-action-ensure-drinking-water-safe-microplastics-pharmaceuticals-and.

⁷ 42 U.S.C. § 300g-1(b)(1)(B)(ii).

⁸ Comment Letter at 3. 

⁹ See https://www.epa.gov/ccl/basic-information-ccl-and-regulatory-determination and 42 U.S.C. § 300j-4(a)(2)(B)(i).  According to USEPA, the CCL and UCMR are related in two ways: (1) USEPA will consider contaminants from the CCL in selecting contaminants for listing in the UCMR, and (2) data collected under the UCMR can inform USEPA’s consideration for future CCLs.  42 U.S.C. § 300g-1(b)(1)(B)(ii).