Quantifying Rooftop Rainwater Harvest Potential: Case of Takoradi Polytechnic in Takoradi, Ghana

Rooftop rainwater harvesting potential as a source of water supply has been examined. The observed monthly rainfall records of 31 years and the current total roof area of facilities at Takoradi Polytechnic main campus as the catchment area were used. Using the simple water balance model to determine the potential for rain water harvesting, the result shows that existing structures totaling a surface area of 15069.18 m2 can harvest 9666.1 m3 of water annually which will reduce the institution's dependency on public supply system (GWCL) by 55.5% at a cost of GH? 83, 232.859 when a 6000 m3 storage tank is installed. The study recommends on the necessity of installing rooftop rainwater harvesting system so as to decrease dependency on public supply system, its inherent challenges and reduction of cost.