Last month, the U.S. Environmental Protection Agency (EPA) announced the draft Sixth Contaminant Candidate List (CCL 6) under the Safe Drinking Water Act (SDWA) and released it for public comment. CCL 6 identifies contaminants that are not yet regulated but are known or anticipated to occur in public water systems and may require future regulation. The draft list includes four contaminant groups — microplastics, pharmaceuticals, per‑ and polyfluoroalkyl substances (PFAS), and disinfection byproducts — along with 75 individual chemicals and nine microbes that may be found in drinking water. Although PFAS were included on prior lists, this is the first time the EPA has designated microplastics or pharmaceuticals as priority contaminant groups. Inclusion on the draft CCL 6 signals an emerging concern about these new contaminant groups and the potential for future regulatory action.