Efficient water distribution is one of the basics for a normal living in a modern society. Water distribution systems (WDS) enable efficient water supply, if they are properly constructed, maintained and managed. WDS are made of many components, which are connected together and have to work coordinated. Because of complexity of these systems it is difficult to determine pressures and flows in this networks. Nowdays network operators are using hydraulic models to provide these hydraulic quantites. This graduation thesis is showing how to build a hydraulic model, calibrating it and using it in the hydraulic analysis of WDS of Naklo. The public utility Kranj, which is operating with WDS Naklo, has built a new transport pipeline. The plan is to connect this pipeline with WDS Tržič, which would also become a new and replace the current water source for WDS Naklo. I elaborated hydraulic analyses for two possible pressure boundary conditions on inlet in WDS Naklo from WDS Tržič. The third hydraulic analysis was on the connection between WDS Naklo and WDS Kranj. The WDS Kranj would be supplied by additional water quantities from WDS Tržič. Building these hydraulic models and elaborating the hydraulic analyses was done using the GIS software Qgis, its plugin qgis-epanet and hydraulic simulation software EPANET 2.0.