Assembly (10) for measuring a leakage in a drinking water supply system, with a backflow preventer (12), wherein the backflow preventer (12) is opened if there is a pressure drop caused by drinking water consumption downstream of the backflow preventer (12) as viewed in a flow direction of the drinking water, and wherein the backflow preventer (12) is closed if there is no pressure drop caused by drinking water consumption downstream of the backflow preventer (12), as viewed in the flow direction of the drinking water, with a volume flow meter (13) connected in parallel to the backflow preventer (12) and via which, if the backflow preventer (12) is closed, a leakage flow of drinking water caused by a leakage in the drinking water supply system downstream of the backflow preventer (12) can be routed, wherein the volume flow meter (13) is integrated into a bypass (14) to the backflow preventer (12).