A good water distribution system should be able to provide water to all planned locations within the city with the necessary pressure head and volume of water to meet different sorts of demand. This research work aims to evaluate the hydraulic performance of the existing Water Distribution System in Injibara Town and the specific objectives were to assess the present water demand and forecast the future demand of the town for the coming 20 years and to evaluate the performance of the distribution system's hydraulic parameters (pressure and velocity) through steady-state analysis. The study used both primary and secondary data types and mostly used quantitative research design. The sample was purposively selected 21 nodes or junctions from the 150 main junctions. To carry out this study, information on water supply systems, water production, and water consumption was acquired from the water utility records. For data analysis the study used Water GEMS V8i, pressure gauge and GPS. Main findings of the study are: The Existing Water Supply distribution system of the town was low water production or low coverage through compared with the current population number (68,657). Additionally, the town has a potential of 42 L/s (2,721.6m3/day) amount of water produced which is 993,384m3/year within 18-hour pumping). This revealed that the performance of the water distribution system under current demand is inefficient. Current demand of water consumption and forecasted water supply demand didn’t balance with the projected population after 20 years (150,545). In addition, the Water loss analysis of the town showed 42.71% of treated water was lost as a total Non-Revenue Water which indicates that the leakage management trends of Injibara town water service system were in poor status, and the utility was given less attention for water loss reduction. On the other hand, the pressure performance evaluation finding showed 85.53% of the total nodes of the town water supply network system pressure value is normal and the velocity performance evaluation finding showed 20.62% of pipe lines were normal that means between 0.6 m/s to 2m/s according to standard. The coefficient of determination (R2) value was 0.9546, it indicates that observed and simulated relation is strong as values tend to one. Keywords: - Water distribution systems, hydraulic performance, modeling, Water GEMS V8i.