The aim of this paper is to show that energy surplus indices, such as resilience index, besides providing a very good indirect measure of water distribution network reliability, also represent a valuable and effective indicator of network robustness under alternative network scenarios. It can thus be profitably used for network design under conditions of uncertain future demands. The methodology adopted consisted of: (a) multi-objective design optimization performed in order to minimize construction costs while maximizing the resilience index; and (b) retrospective performance assessment of the alternative solutions of the Pareto front obtained, under demand conditions far from those assumed during the design phase. Two case studies of different topological complexity were considered. Results showed that the resilience index, which is one of the most effective indirect indices of reliability, represents a very good measure of robustness as well.