Feasibility of harvesting roof top water in an engineering college campus is studied using a stochastically generated daily rainfall series. It has been shown that even though sufficient amount of water is available, possibility of harvesting rainwater is limited because of limitations in the storage that can be provided. It is found that the amount, which can be harvested with a limited storage capacity, meets the demand in the institution on about 115 days, in a normal rainfall year. A cost analysis is presented. Some 'usually not discussed aspects' of the system are also discussed.