Critical Review of Microbial Risk Assessment Tools for Small Drinking Water Systems

The objective of this thesis is to evaluate existing microbial risk assessment tools for small drinking water systems, and to identify directions for improvement. Existing drinking water risk assessment tools are evaluated to determine how well they incorporate the Multiple Barrier Approach to drinking water safety and identify vulnerabilities in water system barriers. The evaluation includes a desktop study using documented waterborne disease outbreaks, and a field study based on inspections of small water systems serving residential developments. The desktop and field studies identified a number of shortcomings in the existing assessment tools. Significantly, the selected assessment tools do not reflect the inter-connected nature of water system barriers. This thesis includes recommendations regarding a framework for development of a vulnerability assessment tool for small drinking water systems based on Interval Type-2 Fuzzy Logic Systems and perceptual computing programming architecture, which could address shortcomings of existing risk assessment tools.