Residential Point-of-Use (POU) Filters Can Be Used to Monitor Multiple Metals in Drinking Water

Abstract

Current drinking water grab sampling is insufficient for monitoring metals that have location-dependent or temporally variable concentrations. This study evaluated the potential of three widely used residential POU filters to serve as volume-integrated monitoring devices for multiple metals. We investigated the two criteria for metals to be monitored by POU filters of (1) complete removal and (2) subsequent complete extraction. To assess the first criterion, lead, hexavalent chromium, arsenate, copper, manganese, and zinc were loaded onto filters both separately using lab-prepared water and together using spiked St. Louis tap water. While cationic metals were robustly retained on the filter media (72-100%), hexavalent chromium and arsenate had lower removal extents (11-62%). To examine the second criterion, metals that had accumulated on the filter media were extracted for quantitative analysis. Extraction methods completely recovered the accumulated metals (87-110%). Volume-averaged concentrations of metals in the incoming water could be quantified based on the mass of metals extracted and information about the cumulative volume of water processed. We demonstrated that POU filters can be used as multipurpose tools to both remove multiple metals from drinking water and monitor incoming water quality over the duration of filter use.

Keywords: arsenate; copper; hexavalent chromium; lead; manganese; residential POU filters; volume-integrated monitoring devices; zinc.