Recent global events have highlighted the vulnerability of drinking water resources to accidental and intentional contamination with bio-threat agents. To insure the safety of drinking water, source water and distribution systems must be monitored for the presence of waterborne pathogens. Comprehensive monitoring of drinking water for these pathogens requires a considerable concentration step that must effectively consolidate viruses, bacteria, and protozoa from large volumes of water. Sample preconcentration of pathogens in tap water prior to the use of analytical tools for their identification has been an ongoing challenge in monitoring waterborne pathogens. The challenge is particularly large for detecting the intentional introduction of bio-threat agents.?