In this diploma thesis, which is based on the intensive and factual measuring of the pressures and the pipe flow rates in the existing water supply network Dalj – Aljmaš – Erdut (5.396 inhabitants), a hydraulic mathematical model representing the actual state of the water supply network has been made, described, and calibrated. During the testing of the model, some advantages, as well as some disadvantages of the existing pipeline network, booster stations, water towers, and reservoirs have been observed. Because of the aforementioned disadvantages in the water supply network, an optimization of the pump station Dalj has been suggested. The hydraulic model served as a basis for the costbenefit analysis of building a new booster station. This diploma thesis has been completed within the framework of the project “Development and application of the Croatian qualification framework in the higher education of civil engineers”, carried out by the Faculty of Civil Engineering in Osijek, and the professional practice was done at “Hidroing d.o.o” in Osijek, a company which takes part in the aforesaid project.