Each water supply system has losses that can not be avoided. Losses represent the water that entered the system but did not reach the last user. Before any water loss remedy, it is most important to get acquainted with the losses, collect data, and perform their analysis. The International Water Association (IWA) has, over the last decade, developed a water loss analysis methodology as well as the most effective measures and activities to reduce water losses. IWA has developed Water Loss Efficiency Indicators, which allow for control over losses and better water supply management. In order to measure water losses and carry out their structure, the water balance is used. Through the water balance, the company can detect whether there is any loss of water or income losses. In order to solve the losses more efficiently, the water supply system is divided into smaller independent units, DMA zones. One of the more effective methods of reducing water losses is pressure control. Pressure control is most affected by small breakdowns, which are the most frequent, and solving this problem has a significantly affects the losses. Active leak control is the name for measures that are taken to find water loss in the ground. Which method will be used depends on the system characteristics at the place where test is performed. The most common procedure for locating faults is to hear noise in the water system by acoustic methods (geophones, correlators ...). In the last section of the study are presented examples of successful reduction of water losses in the towns Vinkovci, Tuzla, Kumanovo, Vidin and Sao Paulo.