The main objective of water distribution system optimization is to find the optimal sizes and characteristics of the components of water distribution system, such as pipe diameters, pump heads and maximum power, and tanks storage volume and elevation, from the available commercial choices to provide an adequate quantity of water for drinking, domestic household usage, garden use, firefighting and irrigation. This is achieved by minimizing the operating and capital costs of these components while the constraints (minimum nodal pressure and demand) at the consumer nodes are fulfilled and the hydraulic laws (mass and energy conservations) are maintained. General recent and thorough reviews on the water distribution network (WDN) optimization can be found [1][2][3][4][5][6][7][8]. 