EPA Announces Proposed Regulatory Determinations for the Fifth Contaminant Candidate List

on January 7, 2025, EPA released preliminary determinations for contaminants on the Fifth Contaminant Candidate List, a mechanism under the Safe Drinking Water Act to evaluate drinking water contaminants for potential nationwide regulation. The contaminants that EPA analyzed under the Fifth Contaminant Candidate List were 2-aminotoluene, cylindrospermopsin, ethoprop, microcystins, molybdenum, permethrin, profenofos, tebuconazole and tribufos.  Based on the best available information at this time, EPA’s preliminary determination indicates that the nine contaminants evaluated by the agency do not meet the Safe Drinking Water Act criteria for establishing a nationwide regulation.

Publication of the preliminary regulatory determinations for these nine contaminants in the Federal Register opens the 60-day public comment period. Comments can be submitted to docket number EPA-HQ-OW-2024-0456 on regulations.gov. The EPA will consider and respond to the public comments received. After doing so, the agency plans to publish the final regulatory determinations prior to the statutory deadline of March 2026.

For more information about regulatory determinations, please find them on the EPA’s Regulatory Determinations website.