EPA releases draft list of drinking water contaminants for possible regulation

The Environmental Protection Agency (EPA) published the draft Sixth Contaminant Candidate List (CCL 6) for the next group of contaminants to be considered for regulation under the Safe Drinking Water Act (SDWA). The agency’s proposed list designates microplastics and pharmaceuticals as priority contaminant groups for the first time.

What’s on the list?

The proposed CCL 6 contains:

• 4 chemical groups, including:
  • Microplastics,
  • Pharmaceuticals,
  • Per- and polyfluoroalkyl substances (PFAS), and
  • Disinfection byproducts.
• 75 chemicals; and
• 9 microbes.

EPA may regulate the listed contaminants in the future.

What does the CCL do?

The drinking water CCL is the first part of the process to regulate contaminants in public water systems. The list identifies unregulated contaminants known or anticipated to be present in drinking water that pose the greatest health risk. It helps EPA prioritize which contaminants to evaluate for potential regulation.

The SDWA requires EPA to make regulatory determinations (i.e., whether to develop rules for a contaminant) for at least five contaminants listed on the CCL every 5 years. When the agency determines a contaminant needs to be regulated, it begins the rulemaking process to develop a National Primary Drinking Water Regulation (NPDWR) for the contaminant. The NPDWRs apply to public water systems.

How can I participate?

EPA will receive public comments on the CCL 6 through June 5, 2026. You can send comments to EPA via regulations.gov or by mail. Make sure your submission includes the Docket ID No. EPA-HQ-OW-2022-0946.

Key to remember: The draft list of the next round of drinking water contaminants to be considered for regulation adds priority groups for microplastics and pharmaceuticals.