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An evaluation of new and traditional approaches to monitor drinking water quality in British Columbia Krentz, Corinne Andrea


Microbiological monitoring of drinking water is a critical element in the source-to-tap framework. This research provides an assessment of traditional and alternative approaches to drinking water monitoring, explores new applications for existing indicators and evaluates a new tool to manage fecal contamination in water. British Columbia (BC) Drinking Water Protection Regulation requires that drinking water samples be tested at an accredited laboratory. This creates challenges related to accessibility for some systems. The objective was to evaluate the agreement between indicator bacteria test results obtained with the current approach and an alternative approach using a presence/absence test close to the point of sample collection. Samples were collected from 83 small systems in the South Cariboo, BC. The agreement measured using Cohen’s kappa was moderate to substantial for total coliforms (0.64 ± 0.11) and E. coli (0.73 ± 0.20). The value of monitoring total coliforms and E. coli in parallel is a topic of current debate. The objective was to evaluate the potential for non-E. coli total coliform events to predict E. coli occurrence in subsequent drinking water samples. Life table analysis of microbiological testing data from small systems in BC showed that systems with a positive non-E. coli total coliform result were twice as likely to observe an E. coli-positive result in a subsequent water sample compared to systems that had not tested positive for total coliforms previously (RR=2.04). Routine drinking water samples containing indicator bacteria are not analyzed further to investigate sources of fecal contamination. The objective was to develop a tool to identify fecal contamination sources in BC drinking water and evaluate the tool using water samples with evidence of fecal contamination. Markers associated with human, livestock and wildlife contamination were selected. Singleplex and multiplex polymerase chain reaction (PCR) was used to test contaminated raw water and drinking water samples for presence of host-associated markers. Low sensitivity of the multiplexed reaction limits its use to detect levels of markers present in contaminated drinking water samples. Singleplex PCR using host-associated markers is a promising tool to identify fecal contamination sources in small volumes of raw and drinking water.

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