Settlement Saint Katarina is situated in eastern Istria, in Pićan county. Saint Katarina does not have an established public wastewater drainage system, so its residents have to rely on private drainage, into septic and collecting pits. This type of private drainage can lead to pollution, negative impacts on the environment, and the health of residents due to its permeability. The purpose of this thesis is to evaluate the performance of the public wastewater drainage system, i.e. construction of a separate sewer system that drains sanitary wastewater is presented. With the system itself, an implementation of a biological wastewater treatment device near the settlement of Saint Katarina is expected. AutoCAD 2023 with the Urbano Canalis 11.2 plugin from StudioARS in Matulji was used to create the work. In Urban Canalis, a sewerage network, a hydraulic calculation and the project-necessary drawings were made. In the introductory portion of the thesis, the location and natural characteristics of the system construction area are addressed. Next, the sewer network and its facilities are described. Accordingly, the hydraulic calculation, mass statements, and graphic attachments have been attached.