The subject of this paper is reduction of water losses in the water supply systems of settlements. Water losses are an integral part of each water supply system and represent a major problem in the maintenance of the continuous water supply of end-consumers. In order to manage the losses in water supply systems, there are various methods and techniques for finding and reducing the losses, which are presented in paper. In addition to the general data on water supply systems and their sustainability, the paper deals with the principles of controlling leakage using the DMA zones - the purpose of the DMA zones, designing and establishing DMA zones, maintaining acceptable levels of leakage in DMA zones. Part of the paper presents the Orahovica water supply system. In this section, except in general about the water supply system, system analysis is presented according to IWA methodology. Flow and pressure measurements were carried out and the conceptual solution of the DMA zones showed savings that would be achieved by testing the network and repairing the failures and reducing the pressure. The conceptual solution also envisages the modernization of the supervisory and control system, which will monitor real-time consumption, which is one of the preconditions for reducing losses.