The work presents the results of the analysis of an existing water supply system. It contains a description of the analysed area in which the analysed system was located, as well as its parameters regarding water intakes and transport of water with pumps, the length and diameter of pipes, and a complication of the materials used to construct the network. Water demand accounting for the nature of the consumers using the water supply network was subject to analysis. The influence of changes in the distribution of water within a day for the basic categories of recipients was accounted for. The EPANET 2.0 program for the simulating water supply network operation, made available by the U.S. Environmental Protection Agency through a public-domain licence, was used to construct the model of the system. The obtained results of the simulation allowed for indicating the main problems with the use of the analysed system. Subject to analysis was the pressure pattern in characteristic nodes of the network from which mining companies, industrial plants and residential households were supplied. Usefulness of the developed simulation model in preparing the assessment of future modernization works was confirmed, allowing for the effects of their implementation to be assessed.