A spatial analysis of private well water Escherichia coli contamination in southern Ontario

Research to date has provided limited insight into the complexity of water-borne pathogen transmission. Private well water supplies have been identified as a significant pathway in infectious disease transmission in both the industri- alised and the developing world. Using over 90,000 private well water submission records representing approximately 30,000 unique well locations in south-eastern Ontario, Canada, a spatial analysis was performed in order to delineate clus- ters with elevated risk of E. coli contamination using 5 years of data (2008-2012). Analyses were performed for all years independently and subsequently compared to each other. Numerous statistically significant clusters were identified and both geographic stability and variation over time were examined. Through the identification of spatial and temporal pat- terns, this study provides the basis for future investigations into the underlying causes of bacterial groundwater contami- nation, while identifying geographic regions that merit particular attention to public health interventions and improvement of water quality.