This report summarizes results from three water security risk communication message mapping workshops conducted by U.S. EPA’s National Homeland Security Research Center. It provides information about effective message development and delivery that could be useful to water sector organizations as they develop their respective risk communication plans. Message mapping is a process by which users can predict 95 percent of questions likely to be asked by the media and others following an incident, prepare clear and concise answers to the questions along with supporting information ahead of time, and practice effective message delivery before a crisis occurs.