This paper proposes a conceptual model for selecting the centralization level for wastewater management in urban areas, which is associated with main sewage collectors and wastewater treatment facilities. The model is supported in the Analytical Hierarchy Process (AHP) and Cost-Benefit Analysis. Additionally, the model is based on the results of variables and indicators identified previously through an expert consultation process and prioritized by Ranking and Rating Multi-criteria Analysis. Three municipalities of Colombia were used as case studies for model validation purposes. As a result, decentralized plans can be a viable option when their associated benefits are quantified.