Todini (2000) defined the Resilience Index as the relation between the power per unit weight dissipated by the WDN and the power per unit weight available to be dissipated. The first term is the power per unit weight spent in form of friction and minor losses, by the configuration of pipes, to give the service consumed in each node of the WDN inform of pressure and demand. The second term is the power per unit weight given to the system by the reservoir (s) and/or the pump (s) minus the optimal one, which corresponds to the case of minimum pressure in each node giving the demanded discharge. The main objective of this research work is to look for that power per unit of weight dissipated by the WDN which would be equal to the power available by means of replacement of certain pipes in the WDN. In this way the reliability degree of the WDN is increased as well as the capacity of the WDN to transport the water under minimum conditions of pressure and demand. To obtain this in an optimal form, one must affect the power per unit of weight that is consumed by the WDN during the process; this power is the one dissipated by hydraulic friction and minor losses inside the pipes. The developed methodology can select, step by step, which single pipeline should be replaced to obtain the maximum increase in the Resilience Index. In doing so, the pressure at the entrance to the network can be reduced, increasing the pressure uniformity and decreasing water leaks. The process must stop either when there is a water quality problem due to the increase in retention time or when the replacement costs are greater than the savings due to leaks reduction. In that way the operator can optimize its infrastructure replacement investments. This paper was presented at the 8th Annual Water Distribution Systems Analysis Symposium which was held with the generous support of Awwa Research Foundation (AwwaRF).