In the final paper, the preliminary design of the water supply and sewerage installation for a family house in Rijeka is described and prepared. The design of the residential building was previously given. The residential building consists of ground floor and first floor. The objectives of the work include the development of the conceptual design of the home installation of water supply and sewerage, hydraulic calculations of cold and hot water, hydraulic calculation of sanitary and storm sewers and the calculation of the absorption well. An integral part of the work is the preparation of evidence of measures and cost estimates. The paper draws in detail and describes the project of plumbing installation from the house connection, through the water meter shaft to the layout and position of installations in the building itself, on the ground floor and attic. Hot water is heated by electric boilers from which hot water is conducted to the water supply. A preliminary design has been prepared for the sewerage system, which includes the drainage of wastewater from sanitary items into the pipe network to the public sewerage system. The drainage of the storm sewer is designed so that the water flowing from the roof collects in gutters and is drained to the absorption well via verticals and a yard network. All designs were made in AutoCAD 2014. In order for the plumbing to work properly and be in line with the norms, the calculations came to the values of optimal flow rates and pipe choices. It was concluded that all conditions were met according to the given norms and Regulations for the introduction of water supply and sewerage in the given facility and the installation of storm sewer drainage.