In the following master's thesis the topics that have been processed narrate the operation and maintenance of the water supply system. The first part of the thesis explains the partition of construction objects as well as parts of the water supply system such as water abstraction from nature, water cleaning and processing devices, pumping stations, reservoirs, supply pipelines and water supply networks. Moreover, the classification of water supply systems according to their modes and water inflow using gravity and a variety of pumping water supply systems has been processed likewise. Part two of the thesis deals with topics related to the maintenance of water supply systems. More specifically, styles and theoretical methods of maintaining water supply systems. In addition to that, this part also describes the methodological settings of the FMEA method, the expenses of maintaining water supply systems, the losses of water in water supply systems as well as detecting the previously mentioned losses. The more minutely handled topics are the supervisory control system (NUS), the application of the IWA methodology as well as the method of maintaining water supply systems according to the EN 805 norm developed by the European Union. Lastly, the thesis describes the water supply system of Vinkovci that has recently become a part of the Regional water supply system ˝Istočna Slavonija˝. The water supply system Vinkovci is depicted in detail with all its basic characteristics including methods of operation and maintenance. Through statistical analysis and data relevant to specific time periods, the flaws of this system have been processed as well as the water usage in the allocated region of Vinkovci, water quality analysis, losses of water throughout the years, the application of the IWA methodology, the maintenance of pipelines as well as the network belonging to the water supply of Vinkovci and finally the detection of field failures and ways of fixing them.