Clean Water: What is Acceptable Microbial Risk?

It is a familiar scenario experienced around the world: an outbreak of gastrointestinal illness suddenly emerges in a community, and no one knows where it came from or how to stop it. At the start of the outbreak, only a few people are affected, most often the very old and the very young. As the outbreak worsens, more and more people fall ill, and people who were weak or unwell may develop life-threatening complications. Such outbreaks sometimes originate from a source that most people in the United States and other developed countries trust unquestioningly: drinking water. This report examines the risks related to pathogens in the water supply and puts forth recommendations for areas of research, communication needs, and methods of microbial risk assessment.