The Master thesis covers the hydraulic analysis of the water supply system of Kostanjevica na Krki. The emphasis of the thesis is on methods for water loss identification. While collecting suitable data several unknown hydraulic quantities of the water supply system that are not measured or are just approximations of true measured values. These challenges, which made it difficult to construct a hydraulic model, led me to elaborating suggestions and a system for quality data collection and measurements for hydraulic modeling of water supply systems. This way I elaborated a measurement scheme that did not involve only the important hydraulic structures on the water supply system, but also the newly proposed DMA zones. The number of measurement locations is can be arbitrary, while I focused on a scheme that would ensure the collection of sufficient quality data to form a calibrated hydraulic model. This would guarantee sufficient measurement data for a calibration process.