To face population inflation and redistribute the population away from the narrow bar of the Nile Valley of Egypt, the Egyptian government starts establishing new cities. Assiut new city was planned to attract the population by constructing residential units, gardens, and a social club. On the other hand, an industrial area was established that includes several factories for different industries. Assiut new city was provided with the necessary infrastructure such as water networks to distribute clean and safe water that people need. Water consumption depends on the future population and city expansion areas. It affects the hydraulic performance of the water network. Hydraulic studies are essential to protect the pipe networks from cracks or blockages due to mud passing inside it and rugged terrain levels. This study aims to evaluate the hydraulic performance of the networks in terms of velocities, pressures and water age under different timing stages from starting the city till the stage of saturation with population at the year 2050. Moreover, the performance of the pumps in the existing pump station is evaluated. Present study is performed using a numerical model overcoming the difficulties of using physical models or field studies which are time and money consuming. A numerical model of Assiut new city pipes network is built using WaterGEMS. The model's input data, such as the pipe diameters, lengths, flow rates, etc., are collected from different sources. The model results show that for saturation of the city with people (the year 2050), the minimum and maximum pressures in the pipes at the peak hour are 34 and 70 meters of water, respectively. Based on these pressures, the flow velocities in the pipes range from 0.01 to 2.5 m/s. The low velocity is noticed in most of the pipes in the network because of the low flow rates and large pipe diameters. This low velocity may be lead to increase the chance of sedimentation in those pipes and the water age. For the stages before the saturation, the situation was worth, especially for the velocity.