This book focuses on 21 case studies (10 waterborne disease outbreaks, 7 cases of severe chemical contamination and 4 close calls) that are written, as far as the publicly accessible evidence allows, from the perspective of front-line personnel. The intent of this book is to create a story line for each case that will allow front line personnel to imagine themselves in these circumstances and to consider how those things that failed could be relevant to them for assuring the safety of their own system.