The aim of this study was to evaluate the performance of the existing water supply system of Adama Town by considering direct and indirect performance measurements. The paper also investigates the application of technical performance index to evaluate the operational performance of the water distribution system and to easily identify the critical areas in the network. The evaluation carried out based on WaterNetGen tools an extension of EPANET to attain direct performance measurement and Minitab16 software to analyze primary data to achieved indirect performance measurement. Based on water tap flows result, most of the residences got water at night time and were not satisfied with the town water supply services. The greatest minimum slack pressure and velocity occurred in a small area of the network, and the global technical performance index of pressure and velocity were 35.75% and 46.19%, respectively.