A significant percentage of Water Distribution Systems' operation costs is due to energy consumption on pumping systems as well as lost water due to leakages. The main reason of these high costs is a non-optimized pumping pattern that leads to excessive overall pressure on the network. This study presents a methodology that permits to find what would be the optimal pumping patter in order to minimize the operation costs. The optimization is done through a GA-EPANET combined process and includes Unique Speed Pumps and Variable Speed Pumps as possible solution for the system.