This slide presentation outlines an incident in the distribution of the City of Hamilton, Ontario, Canada that compelled the Medical Officer of Health to issue a drinking water advisory to an area encompassing approximately 3,200 residences. City of Hamilton staff responded with a notification campaign and for the duration of the drinking water advisory staff provided water at three locations within the affected area. Within one week, all sampling and testing confirmed that the water system was safe to return to service and the advisory was lifted. The presentation outlines several protocols and procedures for improvement including: exploiting the bi-directional link; using customer service information to delineate the affected area; leveraging geographic information systems (GIS) technology to quickly map the limits of the system that is affected and establish the required number of notices; and, development of a prescriptive operating procedure for organizing staff on the ground and ensuring delivery to all affected residences.