Bacteriological testing of private well water: a trends and guidelines assessment using five years of submissions data from southeastern Ontario.

OBJECTIVE: Rural populations are at an elevated risk of gastrointestinal illness, as they are dependent on private groundwater sources, and water quality remains the responsibility of the owner. Previous research suggests that only a minority of well water owners test their wells for bacteriological contamination. The aim of this study was to use testing records, in conjunction with current provincial guidelines, to assess submission rates and temporal trends in southeastern Ontario.
METHODS: Using five years of data (2008-2012) from the Public Health Ontario Laboratory in Kingston, Ontario, submissions of well water samples from unique properties (identified through geocoding) were descriptively analyzed. Temporal trends in guideline compliance were tested using a Cochran Armitage test. Finally, correlations between time and submission numbers were investigated using a 10-year provincial dataset to identify long-term temporal trends.
RESULTS: There were 107,547 submissions in the five years studied, 84% of which were geocoded, culminating in 30,687 unique properties. Although 11%-12% of owners met the guidelines in any given year, only 0.3% met them every year in the five-year study. Statistically significant decreases were found temporally both in the number of properties that met current guidelines and in all samples tested.
CONCLUSIONS: This study is the first to use submission records, rather than surveys, to definitively demonstrate that private well water submission guidelines are not being met in Ontario. However, there are no consistent guidelines across the country or continent, and limited supporting scientific literature is available. Significant research is required to develop evidence-based policies.