Removal of perfluoroalkyl and polyfluoroalkyl substances from tap water by means of point-of-use treatment: A review

: Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are widely used synthetic chemicals known for their environmental persistence and adverse health effects. For this reason, they have come under increasing scrutiny in drinking water, with several groundbreaking drinking water regulations adopted recently in the US and the EU. Nevertheless, conventional treatment processes often fail to remove PFAS effectively, raising concerns about drinking water quality and consumer health. More advanced treatment processes can remove PFAS with varying success from drinking water treatment plants. Using similar technology to that used in centralized PFAS treatment, many types of point-of-use/point-of-entry (POU/POE) water treatment devices are also commercially available. Herein, an overview of the literature regarding POU/POE efficacy in the removal of PFAS from tap water was compiled and critically discussed. Generally, they employ treatment technologies like granular activated carbon, ion exchange, and reverse osmosis to remove PFAS contamination. Despite their laboratory testing and often certification for removal of perfluorooctanoic and perfluorooctanesulfonic acid and other PFAS in tap water, in most cases their efficacy in actual use has yet to be well characterized. In particular, inconsistent testing and insufficient real-life studies complicate assessments of their long-term performance, especially against short-chain PFAS. Furthermore, improperly maintained activated carbon systems might even raise PFAS levels in purified water. Only a few peer-reviewed studies have measured PFAS levels at the tap after POU/POE treatment, with just five assessing removal efficiency in real-life scenarios. Limited to the findings described, not all filters were demonstrated to be effective, especially against short-chain PFAS. Additionally, inconsistent testing methods that do not follow standard guidelines make it hard to compare filter results, and the long-term performance of these systems remains uncertain. More occurrence studies are essential to verify performance over time and understand exposure to these contaminants through water treated by household systems.