The Master’s Thesis examines agglomerations where the municipalities are bound by the requirements of the Operational Programme to ensure the discharge of utility waste water into the sewerage system within the prescribed deadlines, and to then provide waste water treatment at a suitable plant. Based on the analysis of SWTPs up to 2000 PE, which are suitable for smaller settlements, we selected the optimal solution for the discharge and treatment of utility waste water from selected inhabited localities. The explanations for the decisions are provided both from a technical and an economic standpoint. The two critera, important when deciding on the feasibility of a project, are the financial and economic analyses. When analysing costs, we compared the investment, maintenance, and operating costs, which are borne by the utility infrastructure operator after the conlcuded investment project. When it comes to the town of Šentilj, we compared the investment and maintenance costs between two types of SWTPs: a SBR system and constructed wetlands.