The purpose of this study is to propose the optimal water supply control and management plan for minimizing power usage by water distribution pumps. The key topic of this study is to determine from which treatment plants water should be supplied, and through which supply stations it should be distributed. This study devised an optimal model of the ‘route/flow decision problem’ for minimizing power use in the water distribution system while meeting demand in the distributing areas, and formulated the model by means of mixed integer linear programming (MILP). Then to validate the MILP model we attempted a case study in an actual water distribution system. The research demonstrated the effectiveness of the proposed optimization when applied to minimizing power usage in water operation.