A pathogenic agnostic water processing method using large-volume dead-end ultrafiltration: A multi-laboratory performance study.

Treated water systems are critical infrastructures for public health, but can be vulnerable to contamination, whether intentional or accidental. The ability to detect water-transmitted pathogens and biological agents in potable water is critical to effectively respond to and remediate a contamination event or waterborne outbreak. The Protocol for the Recovery and Concentration of Biological Agents in Water samples, or water processing protocol (WPP), was developed for use during such events. The WPP can be used on either 100-L of water concentrated by ultrafilters in the field or unconcentrated 1-L grab samples. The WPP is pathogen agnostic, as is comprised of two workflows that use size selection to capture and concentrate biological agents from parasites down to toxins. A single-laboratory evaluation was conducted by CDC, followed by a multi-laboratory validation (MLV) study with five state public health laboratories. Prior to the MLV, state laboratory participants received in-person training which was followed by training exercises performed in their laboratories. WPP performance was assessed by percent recovery using REXEED-25S ultrafiltered tap water samples seeded with B. anthracis and MS2 coliphage. A bridging study also evaluated different ultrafilter manufacturers for a robust supply chain during an emergency response. The WPP demonstrated ∼50% recovery efficiency for both targets across all filters. During the bridging study, ELISIO-25H performed slightly better for B. anthracis recovery and participants reported a better user experience with ELISIO-25H compared to Xevonta Hi 23 filters. The WPP serves as an essential method for public health readiness to adequately respond to and remediate water system contamination events and waterborne outbreaks.