Water distribution system (WDS) is an essential component of the entire water supply systems. It represents a vital component of the urban infrastructures that requires significant investment. The basic hydraulic equations describing any WDS are non-linear algebraic equations which must be solved iteratively. Genetic algorithms (GA) are currently one of the state-of-the-art techniques for the optimization of engineering systems including water network design and rehabilitation. They are capable of finding near optimal cost solutions to these problems given certain cost and hydraulic parameters. In this study, an anonymous WDS in Egypt has been selected and designed/rehabilitated using GA under deterministic conditions as single objective and as multi-objective problem. The obtained solutions were compared to the results obtained from the ordinary design using non-optimal methods. Results indicated that GA capable of obtaining a robust WDS with least cost. Multiobjective solution that includes robustness or water quality objective as the 3rd objective could be obtained giving the trade-off curves of the WDS.