Drinking Water Contaminant Candidate List (CCL) and Regulatory Determination

  • Regulatory Determination 5

    January 15, 2025 - EPA announced the preliminary regulatory determinations for nine contaminants on the Fifth Contaminant Candidate List (CCL 5). Read more.

  • Contaminant Candidate List 6

    April 19, 2023 - The 60-day submission window has officially closed for public nominations of chemicals, microbes, or other substances that are not currently regulated in drinking water for possible inclusion on the Sixth Contaminant Candidate List (CCL 6). Read more.

  • Contaminant Candidate List 5

    November 14, 2022 - EPA published the Fifth Contaminant Candidate List (CCL 5) that includes 66 chemicals, three chemical groups (per- and polyfluoroalkyl substances (PFAS), cyanotoxins, and disinfection byproducts (DBPs)), and 12 microbes. Read more.

  • EPA evaluates substances that may be in your drinking water by developing Contaminant Candidate Lists and periodically issuing a Regulatory Determination. Learn about the CCL and Regulatory Determination.

About the Drinking Water CCL

Drinking Water Reservior
The Contaminant Candidate List (CCL) is a list of drinking water contaminants that are known or anticipated to occur in public water systems and are not currently subject to EPA drinking water regulations.

Regulatory Determination

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The Safe Drinking Water Act requires EPA to periodically decide whether or not to regulate at least five contaminants on the Contaminant Candidate List. This action is called Regulatory Determination.
Contact Us About the CCL and Regulatory Determinations to ask a question, provide feedback, or report a problem.
Last updated on June 17, 2025