Assessing the Geographic and Socioeconomic Determinants of Private Well Water Testing Practices in Southern Ontario

Abstract

Purpose: An estimated 4.3 million Canadians use private wells for daily water consumption, however well testing rates are declining, potentially resulting in an increased risk of exposure to groundwater contaminants associated with acute gastrointestinal infections (AGIs). Regular testing of well water is recommended to reduce the risk of consuming contaminated groundwater. Methods: This study used a large dataset composed of well testing and well construction data maintained by the government of Ontario. All tests conducted in southern Ontario between 2012 and 2016 were included. Log-binomial regression was used to investigate the association between SES and well water testing practices, with season and index test status included as covariates. Rurality, based on population density, was assessed as an effect modifier of this relationship. Results: The dataset contained information for 417,406 individual wells, 114,820 (27.51%) of which were tested during the study period, with two thirds (66.72%) of these sampled more than once. In urban (>400 people/km2) and peri-urban regions (>150 and <400 people/km2), wells located in low socioeconomic status (SES) areas were 14% and 15% less likely to be tested compared to high SES areas (RR: 0.86 (0.78, 0.95) and RR: 0.85 (0.76, 0.94), respectively). In rural regions (<150 people/km2), wells located in low SES areas were 13% more likely to be tested compared to high SES areas (RR: 1.13 (1.11, 1.15)). SES was not significantly associated with repeat testing in urban/peri-urban regions and was weakly associated in rural regions (RR = 1.06 (1.04, 1.07)). Positive index tests were associated with a 17% increased likelihood of repeat testing when compared to negative index tests, while accounting for the effect of season and SES (RR = 1.17 (1.16, 1.18)) Conclusion: Rurality and SES are important predictors of the decision to test a well, with index test status the most influential predictor of repeated well testing. Further research is required to assess the influence of SES at an individual level. These findings provide important information for public health agencies in the context of strategic and targeted water testing promotion.