Potential Climatic Indicators for Water Contamination and Consequent Drinking Water Disease Outbreaks

Disease outbreaks occurring in drinking water has become an high profile issue since the E. coli O7:H157 outbreak which occurred in Walkerton in 2000. Public Health Officers and water users would like to be able to assess potential risks with higher accuracy in order to avoid the pitfall of issuing too many false positive warnings and too few false negative ones. Research undertaken in the U.S. has demonstrated a link between high precipitation events and waterborne disease outbreaks¹.

This paper uses a forensic analysis of weather events preceding confirmed waterborne disease outbreaks across Canada in an attempt to identify climate thresholds for potential water source contamination and therefore increased risk for waterborne disease. These thresholds can be combined with susceptibility (history of waterborne disease outbreaks; inadequate water treatment practices; treatment failures, maintenance and malfunctions) in order to assess vulnerability more comprehensively. Given this type of information, water users can increase monitoring, alter treatment practices, issue alerts or, in extremely high risk areas, stop water intake temporarily, in order to protect the population.

¹Curriero, FC, Patz, JA, Rose, JB, Lele, S (2001). Analysis of the Association between Extreme Precipitation and Waterborne Disease Outbreaks in the United States, 1948-1994. American Journal of Public Health (91): 1194-1199