This research was conducted in Jigjiga town especially in Duda-Hido District to assess the performance of the water supply system and analyzes the water losses. Water cad software was used to model of the existing water supply systems. Both primary and secondary data were collected in field and water supply and sewarge authority of Jigjiga town respectively. from the water loss analysis for the period 1999-2007, the average water loss rate was 28.3%. From hydraulic performance analysis validation and calibration shows the regression relation and model accounts for 96% of the similarities and this shows that there is a strong correlation between observed and simulated values. From extended period and peak hour demand simulation 10% of nodes are below the minimum allowable pressures and 34% nodes are in the permissible pressure ranges. Additionally, for off-peak hour demand, it was obtained that 8% of nodes in the distribution system were exposed to extremely high pressure (100 H2O) and 58% pressure obtained between 70 and 100 H2O. At low usage hours, no nodes get water at optimal pressure. In addition to this, flow velocity in each pipes was below 0. 6m/s, which is lower than the recommended value. It was concluded that the current water distribution network of district was in poor performance and were not conducted adequate water to the various demand categories of the town. Key Words: Water distribution system, model, performance, water loss, hydraulic parameter, Water CAD, pressure, pipe, Jigjiga.