In water distribution systems, depending on various factors, the failures and leakages occur in service connections, main pipes, and fittings. A significant part of these leakages are not visible at surface, occur underground, and are expressed as unreported leakages. The aim of this study was to investigate and analyze the effect of the unreported leakages occurring on service connections to water loss volume by applying a water loss model based on the minimum night flow and the active leakage control methods. For this aim, a total of 14 district metered areas in Malatya water distribution system were selected as study area. For the water loss model, the minimum night flows were monitored at the lowest consumption times, and the potential leakages points were detected by applying active leakage control method. As a result of this method, a high rate of 77.4% of the identified leakages was observed in service connections. After repairing the leakages detected in the district metered areas, it was determined that a total reduction of approximately 148.9l/s was achieved at minimum night flow. In the study, it was determined that the water loss model developed on the basis of minimum night flow and active leakage control methods provided important contributions to the monitoring, detection and control of the unreported leakages. Furthermore, according to the developed water loss model, it has been determined that a significant portion of the unreported leakages are caused by leakages that occur in the service connections and cause significant water loss.