A warewash machine includes a housing at least in part defining a chamber for cleaning wares and a sump for collecting hot cleaning water that is recirculated through the chamber during cleaning. A drain path is provided for draining cleaning water from the sump and a fresh water input line includes at least a fresh water input that receives fresh water. A waste water heat recovery arrangement includes one or more plate heat exchanger units that transfer heat from the draining cleaning water to the incoming fresh water.