Program automation with waste water heat recovery

Dishwasher, in particular program machine, is recorded with a single cleaning chamber in which to be cleaned (3), a circulating within the cleaning chamber soapy water pump (6) and a further, fresh water (20) delivering pump (11) and a fresh water (20) before rate ligands and heated boiler (9), characterized in that the boiler (9), an active heat exchanger is assigned (18) through which heat in a memory (17) stockpiled waste water to the in the boiler (9) reservoired fresh water (20) is transferred either directly or indirectly, has the active heat exchanger (18) via a umpolbare power supply, such that heat-emitting and heat-absorbing side of the active heat exchanger (18) are interchangeable.