The ideal configuration of wastewater treatment system (WTS) for attending cities specificities has become a complex decision, due to the fact that there are several available technologies, and a diversity of characteristics presented in the scenario of each city. Considering the importance of economic analysis, especially in developing countries, this work aims to demonstrate the economic feasibility considering cost-related indicators for the ideal WTS selection for specific features in these cities. Based on a literature review, 37 main WTS and two economic cost-related indicators (Net Present Value and Annualized Net Present Value) were considered. First of all, using a multi-criteria analysis these WTS were grouped in classes using the ELECTRE TRI method, based on criteria related to efficiency, and the weights were defined by appointments from research specialists in the literature appointments. The economic analysis was performed using the Monte Carlo Simulation (MCS) method, which has been applied specifically to each WTS class, thus generating a framework of economic viability for this context. The WTS with low and high costs were appointed, considering the development level in each applied scenario. This work contributes to expanding the WTS study horizons to select an ideal system, considering the economic aspect.