The paper introduces the development of a methodology for calibrating the simulation model of a water distribution system (WDS), based on a synergy between evolutionary algorithms (EAs) and the numerical modeling of WDSs. In particular, the implemented genetic algorithm (GA) allows the fine tuning, on one hand, of pipe roughness coefficients (depending on their material) and, on the other, of leakage characteristics (parameters and spatial distribution). A case study is also illustrated.