AWWA ACE54243

The objective of this study was to determine routes and severity of pathogen entry into the distribution system and to recommend monitoring and control strategies. This report focuses on the measurement of pathogens external to drinking water pipelines and pressure fluctuations within the distribution system. To determine the opportunity of pathogens to enter thedistribution system, water and soil samples external to the pipe system were analyzed for total coliform, fecal coliform, Bacillus subtilis, Clostridium perfringens, bacteriophage, and enteric viruses. Water utilities were instructed to collect soil and water samples whenever distribution system pipelines were exposed for repairs or construction. Sterile trowels and containers were provided to collect soil samples immediately adjacent to the pipeline from an undisturbed portion of the pit. Water samples (if available) were collected from water within the excavation pit. Both samples were shipped on ice via overnightcarrier to the laboratory for analysis. Both water and soil samples were analyzed for indicator organisms and enteric viruses. Soil samples (10 gm) were mixed with 90 ml of sterile reagent-grade water in a sterile container and mixed for 10 min using a magnetic stirrer. Typically 0.1 to 10 mL of this solution was quickly transferred (to avoid settling) to microbiological media for analysis. Includes 5 references, tables, figures.