Design of the building water supply system is based on the distribution network parameters which determine the required head for water transportation. For the 10-storey dormitory of Peter the Great St.Petersburg Polytechnic University (SPbPU) hydraulic calculations of the existing cold water supply system were done using three automated systems: nanoCAD BIM VK, Autodesk Revit MEP and Dynamo visual programming environment. The results were compared with the developed documentation used in construction of the studied water supply system. The discrepancies in the calculations of various programs were revealed, a way to increase the head in accordance with the current standards was suggested. The analysis showed that nanoCAD BIM VK provided the most accurate results, with deviations not exceeding 5% from manual calculations. Cost comparison of the calculated variants of water supply systems was made. The economic evaluation demonstrated that using Autodesk Revit MEP could lead to 20% higher equipment costs and 60% increased energy consumption compared to other solutions. The software systems that were most suitable for calculating the required head were identified. This study emphasizes the importance of selecting appropriate BIM tools for hydraulic calculations to ensure both regulatory compliance and cost efficiency in water supply system design. The findings are particularly relevant for Russian construction projects where adherence to local standards is crucial.