optiDesigner is Windows software for the optimal design of water distribution systems using 'Genetic Algorithms' (GA). The program uses EPANET (a hydraulic simulator distributed by the US EPA). optiDesigner will design the system pipes and find their minimal cost under a set of constraints such as: minimal and maximal pressures at networks nodes, minimal and maximal velocities at networks pipes, and maximal sources flow. With optiDesigner you can find the most cost effective design, rehabilitation and expansion of your water distribution system.