Abstract: A method and system for optimal design of a water distribution network is provided. Three levels of optimization are available as options for selection by the user and these include least cost optimization, maximum benefit optimization and cost-benefit tradeoff optimization. The optimization models, in accordance with the present invention, include solutions generated by a competent genetic algorithm that can take into account multiple objective functions. Pareto-optimal solutions are produced for the whole range of a budget for the water distribution system. Tradeoff solutions allow engineers to apply engineering judgement to choose the true optimal solution under the specific application being considered.