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Contaminant Candidate List (CCL) and Regulatory Determination
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Contaminant Candidate List 4-CCL 4

The Contaminant Candidate List (CCL) is a list of contaminants that are currently not subject to any proposed or promulgated national primary drinking water regulations, but are known or anticipated to occur in public water systems. Contaminants listed on the CCL may require future regulation under the Safe Drinking Water Act (SDWA). EPA announced the Final CCL 4 on November 17, 2016. On February 20, 2020, the Agency announced preliminary regulatory determinations for contaminants on the CCL 4. Read the preliminary regulatory determinations for contaminants on the CCL 4.

Federal Register Notices

Drinking Water Contaminant Candidate List 4
  • Read the Final CCL 4 Federal Register Notice
  • Read the Draft CCL 4 Federal Register Notice

Read More About CCL 4

  • Overview of the CCL 4 Approach
  • CCL 4 Frequent Questions
  • CCL 4 Technical Support Documents
  • For additional information please visit docket number EPA-HQ-OW-2012-0217 at regulations.gov.

What's on the Final CCL 4

The Final CCL 4 includes 97 chemicals or chemical groups and 12 microbial contaminants. The list includes, among others, chemicals used in commerce, pesticides, biological toxins, disinfection byproducts, pharmaceuticals and waterborne pathogens. These lists can be read by selecting the links below.
  • Final CCL 4 Chemical Contaminants List
    Chemical molecule
  • Final CCL 4 Microbial Contaminants List
    Magnified image of a microbial drinking water contaminant
  • CCL and Regulatory Determination Home
  • Basic Information
  • CCL 5
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  • CCL 1
  • Regulatory Determination 4
  • Regulatory Determination 3
  • Regulatory Determination 2
  • Regulatory Determination 1
  • Types of Drinking Water Contaminants
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Last updated on April 12, 2022