The U.S. Environmental Protection Agency (EPA) has set limits on perfluoroalkyl and polyfluoroalkyl substances (PFAS) in drinking water for the first time, regulating six compounds including PFOA and PFOS at 4 parts per trillion. Public water systems are required to monitor and disclose these contaminants, with a initial three-year monitoring period ending in 2027 and options to reduce levels if necessary.