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.