Assessing well characteristics as risk factors for bacterial contamination of private wells in Wellington-Dufferin-Guelph, Ontario.

This study aims to identify important well characteristics associated with increased odds of bacterial contamination in the Wellington-Dufferin-Guelph public health unit of Southern Ontario. Identifying risk factors associated with bacterial contamination can aid in the mandate of public health units to promote the safety, and facilitate the testing, of drinking water systems to help minimize the risk of illness. Logistic regression models for adverse bacterial test results based on physical well characteristics were created. Models with the lowest Akaike Information Criterion values were examined for consistently identified characteristics. The odds of bacterial contamination in the Wellington-Dufferin-Guelph region are most associated with the age of the well, the season of testing, having a treatment system on the well, and the presence of potential point contamination sources within 50 feet (15.24 m) of the well. While this information can support the design of targeted public health education campaigns, the current model leaves room for improvement, as the predictive abilities of the models based solely on well characteristic data are limited.