The Smart City Quarter “Campagne-Areal” is a project involving 16 new buildings in Innsbruck. The first four buildings have already been built and occupied. They are served by a central block heating system, which provides hot water for space heating and domestic hot water (DHW). Each apartment is equipped with a fresh water station (FWS) for the DHW preparation. The FWSs in all the 52 apartments of one of the buildings are monitored, collecting data on volume flow, flow and return temperature, power, and energy at time intervals between 1 and 2.5 min. The analysis of the detailed data allows for the study of actual DHW consumption and tapping simultaneity in a large multi-family building, which is crucial for the sizing of the system components. Comparing the DHW consumption among the 52 apartments shows the possible range of DHW usage at apartment-level (e.g., different tapping duration, mass flow, time in the day) and the variability over time within individual apartment. The monitoring data are compared to the recommended profiles from the standards (e.g., EN 16147), highlighting discrepancies and identifying unexpected tappings with different energy characteristics. Undetected minor tappings, identified and incorporated into the analysis, notably influence the simultaneity factor calculations. These findings improve the understanding of DHW usage in large multi-family buildings, offering in-sights into its variability and the impact on system dimensioning.