The EPA established Maximum Contaminant Levels (MCLs) and Maximum Contaminant Level Goals (MCLGs) for six per- and polyfluoroalkyl substances (PFAS), made effective June 25, 2024. MCLs are legally enforceable levels for drinking water that consider public health effects and the ability to measure and treat to remove a contaminant, as well as costs and benefits. MCLGs are solely based on potential health effects and are not legal requirements. MCLs and MCLGs were added for perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexanesulfonic acid (PFHxS), hexafluoropropylene oxide dimer (HFPO-DA), perfluorononanoic acid (PFNA), and perfluorobutanesulfonic acid (PFBS).
As part of this new rule, public water systems must complete initial monitoring within three years of the final rule promulgation (2027), and/or use the results of recent previous monitoring, followed by ongoing compliance monitoring. Beginning in 2027, public water systems must also provide the public with PFAS levels in their drinking water. MCL compliance is set at five years of the final rule promulgation (2029). Public water systems are defined as those that have at least 15 service connections and serve 25 people per day for at least 60 days per year.
Federal Register Notice: Final PFAS National Primary Drinking Water Regulation https://www.federalregister.gov/documents/2024/04/26/2024-07773/pfas-national-primary-drinking-water-regulation
EPA Final PFAS National Drinking Water Regulation https://www.epa.gov/sdwa/and-polyfluoroalkyl-substances-pfas