A method for disinfecting a water system of an aircraft includes the introduction of damp hot air at an inlet of the water system by a ground service unit; flushing of the damp hot air from the inlet through water pipes of the water system to an outlet of the water system; and extraction of the damp hot air at the outlet; wherein the damp hot air is flushed into the inlet and out of the outlet over a predefined disinfection period, and wherein the damp hot air has a temperature between 60° C. and 80° C.