Final rule · 2026-05452

Announcement of Final Regulatory Determinations for Contaminants on the Fifth Drinking Water Contaminant Candidate List

The U.S. Environmental Protection Agency (EPA) is announcing final regulatory determinations for nine contaminants listed on the fifth Contaminant Candidate List. Specifically, the Agency is making final determinations not to regulate 2-aminotoluene, cylindrospermopsin, ethoprop, microcystins, molybdenum, permethrin, profenofos, tebuconazole, and tribufos. The Safe Drinking Water Act (SDWA) requires the EPA to make regulatory determinations every five years on at least five unregulated contaminants. A regulatory determination is a decision about whether or not to begin the process to propose and promulgate- a national primary drinking water regulation (NPDWR) for an unregulated contaminant.