The GIS system has permanently entered the current operations of water supply companies. Due to the intensive development of cities and the resulting dynamic development of technical infrastructure, which is inherent in the functioning of the city, more and more extensive functionalities are expected from the GIS application. To fulfil the obligation to ensure continuity of water supply and sewage collection, it is necessary to constantly expand the system, extending it with new possibilities and integrate it with other software used in the company. We expect the created application not only to allow spatial identification of network sections, but also to simulate various operating conditions of the water supply and sewage collection system, and facilitate making current decisions related to the system operation and its regulation. Also, situations in which the system works in conditions that deviate from typical parameters are important. These situations can be caused by breakdowns, increased demand for water or heavy rainfall. To achieve the ability to support decisions independently of the GIS system, it is necessary to properly tare the hydraulic models of the system, and an extensive measurement system from which data is sent to the SCADA system via a data transmission system. The cooperation of the GIS and SCADA systems and hydraulic models allows for the creation of integrated software to support operational services. The paper presents a practical example of integration of the GIS system with hydraulic models of a water and sewage system, as well as available functionalities that allow improving the management of the water and sewage system in Krakow.