On March 14, 2023, the U.S. Environmental Protection Agency (EPA) issued a proposed National Primary Drinking Water Regulation (NPDWR) which, if finalized, would set enforceable limits, known as Maximum Contaminant Levels (MCLs), for six Per- and Polyfluoroalkyl Substances (PFAS). The announcement marks the first time the EPA has proposed to establish a new MCL under the Safe Drinking Water Act in 25 years.