A warewash machine includes a sump for collecting hot cleaning water that is recirculated in the chamber during cleaning, a drain path for draining cleaning water from the sump and a fresh water input line including at least a fresh water input that receives fresh water. A waste water heat recovery arrangement includes a plurality of heat exchange compartments arranged in series flow communication and forming part of the drain path. A waste water input is associated with a first of the heat exchange compartments and a waste water output associated with a last of the heat exchange compartments. Waste water at least partially fills each of the heat exchange compartments. At least part of the fresh water input line passes through each of the heat exchange compartments. Heat from waste water is transferred to fresh water in the drain line within each heat exchange compartment.