To provide protection against the transmission of waterborne disease all public drinking water systems are required to monitor for coliform bacteria at a prescribed frequency. However, waterborne outbreaks have previously been documented in public water systems which have not exceeded these coliform regulations. A comparison of coliform monitoring results in a sample of both community and non-community water systems showed no statistical differences in coliform results between systems in which an outbreak had occurred and systems in which no outbreaks had been reported. Although the results of this study must be interpreted cautiously, the authors feel that public health officials should reevaluate the importance of routine coliform monitoring in their surveillance program for the prevention of waterborne disease.