On February 20, 2020, the United States Environmental Protection Agency (EPA) issued preliminary determinations to regulate two perfluoroalkyl and polyfluoroalkyl (PFAS) compounds in drinking water: perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). In its announcement, the agency noted that it is also gathering and evaluating information to determine if regulation is appropriate for other chemicals in the PFAS family. The EPA’s regulation of PFOS and PFOA in drinking water will follow the national primary drinking water regulation rulemaking process as established by the Safe Drinking Water Act. Thus, the agency will have a two-year period to determine the maximum contamination level (MCL) for PFOS and PFOA. Once it formally proposes the MCL, EPA will have another year and a half to finalize the drinking water requirement. According to EPA, the preliminary determinations are actions EPA is taking under the agency’s PFAS Action Plan, which is focused on enhancing how the agency researches, monitors, detects and addresses PFAS. There will be a 60-day comment period on the preliminary determinations after it is published in the Federal Register.