Efficacy of Pitcher Filters For Drinking Water Lead Reduction: A Challenge and Demonstration Study in Denver, CO

Abstract

The effectiveness of point-of-use filters for removing lead mainly and other metals (copper, iron, manganese, and zinc) without removing fluoride in drinking water were evaluated under controlled laboratory and field environments in Denver Water. Corrosion control treatment racks (control at pH 7.8 adjusted to 8.8 and 1 mg/L as PO4 of orthophosphate) at two different water treatment plants were used to examine lead removal in five different NSF/ANSI-42 and NSF/ANSI-53 certified pitcher filters. The lead concentration in the challenge water from the control racks range between 31-97 ppb and all 5 filters had >94% removal efficiency. In general, the challenge water from orthophosphate racks had lower lead compared to the control racks, however, 2 filters (pitcher filter E [activated carbon, oxidation reduction alloy, dual cation/anion exchange resin, and non-woven membrane] and filter C [Carbon based filter media with electrostatic properties]) failed to consistent reduce lead to below the NSF standard of 5 ppb. The pitcher filter E which was designed to remove fluoride consistently removed the fluoride to non-detectable levels. Pitcher filter A (activated carbon and cation exchange filter) which was not designed to remove fluoride removed >90% of the fluoride in our study. Based on the filter challenge study, pitcher filter B were selected as the most appropriate for Denver Water’s water quality. Field demonstration study samples were collected from at least 50 different sites twice a year between 2020 and 2021 in Denver, CO. All distributed filters in the field study reduced lead concentration under AL except one sample with negative concentration difference between filtered (40.8 ppb) and unfiltered samples (1.4 ppb). The results add to an extensive body of evidence water quality or filter operating conditions may affect lead removal efficacy.