Rainwater Quality in Ibadan (Nigeria): Effect of Short Term Storage in Surface and Underground Tanks

Omolara Lade, Olatunde Okunlola

Water is needed in adequate quality and quantity for human consumption. As population increases, demand for water is growing higher. Rainwater harvesting (RWH) is important for sustainable development and has no adverse environmental impacts. It also provides convenience in terms of decreased distance to sources of supply and is less time consuming than surface and groundwater sources. In this study, rainwater was collected from the rooftop and stored for a short term in underground and surface tanks. In total, 26 samples were collected from two RWH storage system. The stored samples were taken to the laboratory for Physico-chemical and biological analysis after days 1, 3, 7, 14, 21 and 28 respectively. Several parameters were included in the analysis: colour, temperature, turbidity, pH, total dissolved solids, total soluble solids, total hardness, alkalinity, dissolved oxygen, nitrate, total coliform and E. coli. The study reveals that the overall quality of water with respect to the WHO and Nigeria standards for drinking fell within the permissible limit. RWH system benefit from water and energy savings thus providing a system that is cost effective. The findings revealed that storage of rainwater in underground tank for a period of 28 days is fit for potable use with simple point-of -use treatment such as filtering and chlorination.