Under the Drinking Water Protection Regulation, drinking water originating from ground water at risk of containing pathogens must be disinfected. This document was developed to assist water suppliers and regulatory authorities in determining when a ground water source is at risk of containing pathogens. It introduces a four-stage process consisting of an initial screening tool checklist followed by incrementally more complex hydrogeologic investigations and monitoring to identify and assess the level of potential health hazard and risk associated with a ground water source.

http://www.health.gov.bc.ca/protect/pdf/garp-gwudi-guidance.pdf