The subject of the paper is the Bialystok water supply network. The studies of the Bialystok water supply network are aimed at identifying new, more rational ways of operation (decreasing the pressure value) and defining the conditions for expansion and modernization of the water supply network, with the particular system analysis as a part of identifying the most dangerous places on the network. The increase of requirements concerning the quality and the time of realisation in the scope of the design studies requires the introduction of computer technology in calculations. The work presents processes based on mapping and refinement of specific conservative states of the water distribution system (SDW), using mathematical modelling taking into account the latest available computer techniques.