Physicochemical characteristics of harvested rainwater under different rooftops in Ikole Local Government Area, Ekiti State, Nigeria

Abstract

Due to scarcity of potable water in most rural and urban settings in Ekiti State, rainwater harvesting from rooftop has been favoured as an alternative source of water supply. This study investigated the physicochemical characteristics of rainwater harvested from four different rooftop sheets in Ikole-Ekiti and its environs. Samples were collected three times from the month of June to August, 2018. Parameters investigated include pH, Total Dissolved Solid (TDS), Turbidity, Electrical Conductivity (EC), Alkalinity, Total Hardness, Ca²⁺, Mg²⁺, Na⁺, K⁺, Fe, Pb, Zn, Al, and Cu. Data obtained were subjected to descriptive statistics to determine the mean and standard deviation and water quality index measured. The result shows that the physicochemical parameters ranges from 8.03-9.17 (pH), 0.47-3.17 NTU (Turbidity), 56.20 -170.43 μs/cm (EC), 30.2-50.53 mg/L (TDS), 18.56-27.58 mg/L (Alkalinity), 19.94-24.08 mg/L (Total Hardness), 8.67-14.93mg/L (SO4 2+), 4.11-11.67mg/L (Cl^-), 0 - 4.62 mg/L (Zn²⁺), 7.11-11.13 mg/L (Calcium), 0.07-1.56 mg/L (Al²⁺), 0.01-0.02 mg/L (Cu²⁺), 9.41-21.33 mg/L (Mg²⁺), 29.04-40.35 mg/L (Na²⁺) and (Fe²⁺) 0.1-0.29 mg/L . Most of the measured parameters were all within permissible water quality standard as recommended by World Health Organizations (WHO) except for the slightly basic character of the rainwater. All measured parameters were high in aluminum sheets and coated rooftops but did not exceed the World Health Organization permissible limit followed by Galvanized zinc rooftop and Panted rooftop. Water Quality Index (WQI) for painted rooftop, aluminum rooftop, galvanized zinc rooftop, and coated rooftop were 3.296, 1.335, 6.078 and 2.629 respectively indicating excellent water quality. The study found that harvested rainwater in the area could be used for domestic purpose with minimum treatment to enhance drinkability.

Keywords: Rainwater, Rooftop, Quality, Health and Permissible limit