A method for assessing and guaranteeing the thermal hygiene efficiency in a multi-tank dishwasher in which there is at least one sensor that transmits a temperature inside at least one treatment zone to a machine control system, in particular to the control system of the multi-tank dishwasher, the method includes: detecting the temperature inside at least one of the treatment zones by the sensor; determining the heat input applied to the items to be cleaned in at least one of the treatment zones on the basis of the temperature determined; comparing the heat input in the at least one treatment zone with a predefined heat input; and, as a function of the result of the comparison of the heat input values, varying the transport speed of the items to be cleaned through the multi-tank dishwasher, or varying the temperature of at least one of the process parameters acting on the heat input values as a control variable in a control loop for at least one of the treatment zones.