Water supply systems are becoming more important, since there are increasing requirements to improve operation whilst improving the environment so that their behaviour can be fully understood and the total process is optimised. This paper presents simulation and control of water supply system of Gaziantep city in Turkey for management purposes. The main objectives are to ensure the behaviour of a water supply system and to regulate the water flow and heads by manipulating the water pumps. The system consists of a sequence of pumping stations that deliver water through pipelines to intermediate storage reservoirs. The model used is obtained using dominant system variables that represent active and passive dynamical elements. The hydraulic models also include the nonlinear coupling between flows and reservoir heads. The polynomial H-infinity optimisation method is used to design a level controller that regulates water flow, and heads through the system. The whole system is simulated, and the results are presented and compared with the real-time measured data. (C) 2002 Elsevier Science Ltd. All rights reserved.