In Rwanda, after 1994 Genocide tremendous efforts have been made in order to improve the water and sanitation sector. In these days, Rwanda government has made efforts in improving available quantity of water in use. Rainwater harvesting is one among of the solution of water scarcity in the country. The objectives of this work is to estimate the water demand, the quantity of rainwater that can be harvested from Integrated Polytechnic Regional College of Karongi (IPRC Karongi) buildings, the design of storage tanks and the implementation possibilities of this project. The required water demand is estimated to 45 liters per capita per day. The data have been analyzed and the calculated quantity of rainwater is 12,296.15m3 per year and the storage capacity is1, 496.24m3. At the end of the work, the result shows that rainwater harvesting technique can save 22% of the bills paid for water every year. We note that the report deals with untreated water for non-consumptive activities. It is recommended to do further research concerning the treatment of rainwater for drinking purposes, so that the students may access the treated rainwater. I suggest implementing this project as soon as possible because of its many advantages.