The invention relates to a fixture and a method for cleaning a drinking water purification system including the following steps: removal of a filter cartridge from a cartridge holder of a filtering unit in a cold water line, insertion of a connection adapter into the cartridge holder to form a fluid connection with the cold water line, connection of a connecting piece of a hot water line to the connection adapter, heating of water with a heater interconnected with the hot water line, delivery of heated water via the connecting piece of the hot water line and the connection adapter into the cold water line.