Skip to content
Goldberg Segalla logo

Environmental Law Monitor

Your Guide to Emerging Issues in Environmental Regulation and Litigation.

Filling up a glass with drinking water from kitchen tap
• Environmental Law Monitor, EPA, SDWA

What’s in the Water? EPA Signals Direction of Future Drinking Water Regulations

Posted by

On April 6, 2026, the U.S. Environmental Protection Agency (EPA) published in the Federal Register its draft Sixth Contaminant Candidate List (CCL), which lists contaminants currently not subject to any national primary drinking water regulations. These contaminants are either presently known or in the future will appear in public water systems and may be subject to future regulations under the Safe Drinking Water Act (SDWA). This draft Sixth CCL contains 75 individual chemicals, 9 microbes, and 4 main chemical groups: disinfection byproducts (DBPs), microplastics, per and polyfluoroalkyl substances (PFAS), and pharmaceuticals.

The CCL essentially acts as the first step in identifying contaminants for future regulation under the SDWA. Inclusion on the CCL does not automatically mean that a contaminant will be regulated in the future but rather provides the initial framework for contaminants that require further investigation. Furthermore, under the SDWA, the EPA must make a regulatory determination for at least five contaminants on the CCL every five years.

The EPA, when evaluating these chemicals, considers the following criteria when making a regulatory determination for the list according to the SDWA:

  • The contaminant may have an adverse effect on the health of persons;
  • The contaminant is known to occur or there is a substantial likelihood that the contaminant will occur in public water systems with a frequency and at levels of public health concern; and
  • In the sole judgment of the Administrator, regulation of such contaminant presents a meaningful opportunity for health risk reduction for persons served by public water systems.

The four chemical groups addressed in this draft Sixth CCL are summarized below:

  • Disinfection Byproducts (DBPs):DBPS are formed when disinfectants used for antimicrobial treatment in drinking water react with natural or man-made materials in water. The EPA’s proposal is to list DBPs as a group. The list includes 27 unregulated DBPs, of which 23 carried over from the CCL 5. Four additional compounds (bromochloroacetonitrile, chloral hydrate, chloronitramide anion, and trichloroacetonitrile) were added based on expert evaluation and potential health concerns.
  • Microplastics:The EPA also proposes listing microplastics as a group on draft Sixth CCL in response to public nominations and advisory recommendations and considers this as a first step toward defining and better understanding public health risks from exposure via drinking water. At the same time, the EPA acknowledges that there are gaps in available data regarding this topic and further research is required to determine the characteristics most associated with adverse health effects, a validated analytic method to detect and analyze concentrations of microplastics in drinking water, sources of microplastics, and a better understating the impact of microplastics occurring in mixtures with other substances to adverse health effects.
  • Per‑ and Polyfluoroalkyl Substances (PFAS): The EPA’s proposal is to include PFAS as a group using the previous CCL 5 structural definition to address the impracticality of evaluating thousands of individual PFAS. Those that are already subject to national drinking water regulations will not be included.
  • Pharmaceuticals:  Last, the EPA proposes listing pharmaceuticals as a group to prioritize research on drugs detected in drinking water. The EPA reviewed literature for newly identified microbes and public nominations for additional pathogens.

Importantly, this draft is an opportunity for those in the various industries that produce or use these chemicals to advocate and provide input on chemicals that could be subject to future regulation by the EPA through the comment process. Therefore, it is critical to review both the draft CCL and the request for comments section, which clearly identifies the specific areas for which the EPA is seeking not only public comment but also supporting data.

The comment period ends on June 5, 2026. One requirement to note is that any comment must contain the specific Docket ID Number, which is Docket ID Number EPA-HQ-OW-2022-0946. Read the full draft list here, which further contains specific instructions on how to send comments to the EPA, and the specific areas for which the EPA is seeking comment and supporting data.