This article describes methods for disinfecting potable water mains subjected to emergency repairs following physical failure of the pipeline. The proper procedures to follow for main disinfection relate to the overall repair operation. The necessary steps include: minimize entry of contaminants into the pipe, remove any contaminants that may have entered the pipe, disinfect any contamination that remains, flush the disinfectant from the pipe, and determine the bacterial quality after disinfection. Each of these steps is discussed in detail.