Water of River Barak that runs through densely populated Silchar city of Assam was taken for evaluation of Water Quality Index(WQI). Water Quality Index is a grade used to represent water quality at particular station at that particular time based on several water quality parameters. The idea is to turn complex water quality into a number that is understandable and usable by all. Important parameters such as pH, Turbidity, Conductivity, Total Dissolved Solids(TDS), Dissolved Oxygen(DO), Residual Chlorine, Chloride and Temperature are taken for the purpose. The study was conducted utilizing a single water sampling method with 7 sampling stations along a stretch of 25 Km as Sonabarighat, Kanakpur, Badrighat, Sadarghat, Karatigram, Annapurnaghat, and Masughat. Weekly data for a period of 3 months was used .The study reveals that Water Quality Index of all stations is in the range of 20 to 40 which indicates water is not polluted and is harmless but turbidity of water is more due to sediment flow.