Assessing the Effectiveness of Point-of-Use Residential Drinking Water Filters for Perfluoroalkyl Substances (PFASs)

Per- and polyfluoroalkyl substances (PFASs) have come under increased scrutiny due to concerns about their potential toxicity and prevalence in the environment, particularly drinking water. PFASs are difficult to remove in full-scale water treatment systems because of their physicochemical properties. Here we evaluated the effectiveness of point-of-use (POU) and point-of-entry (POE) residential drinking water filters in removing a suite of three perfluoroalkyl sulfonic acids, seven perfluoroalkyl carboxylic acids, and six per- and polyfluoroalkyl ether acids in homes in central (n = 61) and southeastern (n = 12) North Carolina. POU systems included countertop and pitcher filters, faucet-mounted filters, activated carbon block refrigerator filters, activated carbon block under-sink filters, under-sink dual-stage filters, and under-sink reverse osmosis filters. All under-sink dual-stage and reverse osmosis filters tested showed near complete removal for all PFASs evaluated. In contrast, all other filters containing activated carbon exhibited variable PFAS removal. In these filters, PFAS removal efficiency was dependent on chain length, with long-chain PFASs (similar to 60-70% removal) being more efficiently removed than short-chain PFASs (similar to 40% removal). A few whole-house activated carbon POE systems (n = 8) were also evaluated; however, results were variable, and in some cases (four of eight systems), increased PFAS levels were observed in the filtered water.