This thesis addresses the construction of a sewage system in urban areas, with a particular focus on the Drenova district in the city of Rijeka. The main objective of the work is to analyze the current state of the sewage network and propose optimal solutions for its upgrade and modernization. The thesis covers key technical aspects of sewage system design, including hydraulic calculations, material selection, and construction and maintenance methods. Special attention is given to environmental protection and the prevention of negative impacts on ecosystems, taking into account the specific geographical and climatic conditions of Rijeka and the surrounding areas. The analysis also includes the socio-economic aspects of the project, such as construction costs, maintenance, and long-term benefits for the population. Through a detailed case study of Drenova, specific solutions and plans for improving the existing system are presented, including the construction of new collectors, modernization of pumping stations, and the introduction of wastewater treatment systems. The results of the study have shown that the proposed measures can significantly improve the efficiency of the sewage system and reduce the risk of flooding and pollution.