The hot water system is a basic component of any commercial food service operation. Water heating, delivery and use represents a significant cost to the operator ranging from $2,000 in a small quick-service restaurant to $50,000 annually in a large full-service restaurant in California. It would make sense that this near-universal water-and-energy using system would evolve to become highly efficient but that is not the case. A century later, the heaters, piping, piping layout and hot water using equipment that make up the typical food service hot water system have changed little in most kitchens, making this a robust opportunity for real energy and water savings. New centralized water heaters and localized water heating technologies will be covered with insights in to compatibility in existing facilities and performance improvements versus conventional water heaters. Case studies of new and emerging technologies will showcase the performance improvements and savings of water heating and preheating technologies used independently and in combination with other best-in-class technologies. The material will cover both new-construction and opportunities for existing facilities.