This thesis presents two conceptual solutions of the wastewater drainage system for villages Škropeti and Novaki Motovunski in Istria. In the first solution, the wastewater of both settlements is drained to a common treatment plant, while in the second solution, the corresponding wastewater treatment plant is built for each settlement. Both systems are performed as a separated distribution system which is defined by the spatial plan of the municipality of Karojba. The collected wastewater is discharged to a wastewater treatment plant that uses submerged aerated fixed filter technology for wastewater treatment. The thesis consist of theoretical and computational part, an approximate cost estimate with the accompanying evidence of measures, draft documentation. In the theoretical part, general data on the location and number of inhabitants are given, geological, climatic, hydrological and pedological characteristics of the area are described, as well as a technical description of the planned sewage system and all its elements. The description of the elements describes their role in the operation of the sewerage system, provides informations about the exact number of each element that is needed, informations about methods of maintenance aswell as methods of testings and how to correctly install each element. The computational part consists of hydraulic calculation, calculation of pumping stations and associated pumping basins and static calculation of collectors. The hydraulic calculation was implemendted using the software Urbano Canalis 10.3. The design documentation consists of the longitudinal profile of the collector, the situation, floor plan and cross-section of the buried and typical pumping station, details of the installation of manholes and the characteristic cross-section of trench. In conclusion a comparison of both solutions was given.