Comparing Three Sampling Designs for Monitoring Coliforms in Small Community Water Systems

摘要

Three sampling designs: weekly, monthly and spatial cluster are compared as to their effectiveness in detecting coliform contamination in small community drinking water systems. Water samples were collected over a one-year period from fifteen drinking water systems in rural communities of Vermont and New Hampshire. Sampling five times per month, whether samples were collected simultaneously at five different sites within a system (spatial cluster) or once a week at the same site, detected between 50 and 100% more contaminated situations than were found by sampling once per month. The spatial cluster design was slightly more sensitive than the weekly sampling design in its ability to detect coliform contamination.