Microbial Pathogen Survival and Extraction from Point-of-Use Filters

The U.S. drinking water supply remains a vulnerable target for potential bioagent release and there is a need to identify the origin and extent of a bioagent release should it occur. In the aftermath of a release, it will prove difficult to retroactively sample enough of our water supply to identify release origin. Previous research reported that household water filters retain microbes, so it was hypothesized that filters could be extracted to identify bioagents. A national drinking water survey was modified to obtain information on the most commonly used household water filters. Based on the survey results, faucet mounted filters manufactured by PUR and Brita were chosen for microbial extraction studies. Based on microbial sorption and extraction tests using activated carbon and individual filter units, a microbial extraction method was developed. The extent to which new and used filters retained viral and bacterial agents was determined, and percent extraction efficiencies of representative bioagents were reported. A tap water manifold was used to expose filters to realistic water usage patterns, and mock-release experiments were performed in which microbial agents were released into the water supply. Filters were extracted five days after being challenged with bioagents and the effect of storing filters at 4 DegreesC was documented.