The technical aspect of this paper is to analyse the harvested rainwater from the hydrological point of view. First of all, the considerable catchment area is found out. Total rainwater which is collected from rooftops of different buildings like departmental buildings and hostel buildings at BCREC Durgapur Campus. Then, hydrological and topographic data of the considered catchment area has been collected. Finally, the water harvesting capacity from different buildings is evaluated. Alongside, a parametric study is done to show the variation of discharge throughout the year. Finally, the potential of harvested water in number of days is estimated to find out the effectiveness of the rainwater harvesting system in BCREC campus.