Longitudinal assessment of point‐of‐use carbon filters for removal of per‐ and polyfluoroalkyl substances from private well water

Abstract Eighteen private well users in North Carolina were recruited to test the performance of under‐sink, activated carbon block water filters to remove per‐ and polyfluoroalkyl substances (PFAS). Monthly sampling was conducted for 8 months. Filters were certified for removal of perfluorooctanoic acid and perfluorooctanesulfonic acid under NSF International certification P473, but not for additional short‐chain perfluoroalkyl acids or perfluoroalkyl ether acids (PFEAs) evaluated in this study. Out of 47 targeted analytes, 17 PFAS were detected in filter influent samples (influent ∑PFAS 4.7–131 ng/L). Mixed‐effects Tobit regression models showed that the filters effectively removed 97%–99% of all influent PFAS, including short‐chain PFEAs, for the entire manufacturer‐recommended lifetime of the device. The prevalence of PFAS above the minimum reporting limits was reduced by 99.5%, and the prevalence of any PFAS above the method detection limits was reduced by 92%. The results provide increased confidence in NSF P473‐certified filters for the removal of PFAS from private well water.