Hydrology for Disaster Management Special Publication of the Nigerian Association of Hydrological Sciences, 2012 Chemical and Physical Properties of Harvested Rainwater from Different Roofing Sheets in Abeokuta, Ogun State

Access to a regular supply of safe water is a basic human right but many people are denied. Rainwater is available for everybody use. This study investigated the physical and chemical properties of rainwater harvested from different catchment roofs in Abeokuta, Ogun Sate. Sterilized buckets were used to collect runoff from five (5) different roofing materials (metal sheets(pan), painted metal sheets, galvanized metal sheets, asbestos(slate) and anodized alluminium) and direct source (control) from June to October, 2010. Sample collection was replicated three times. The runoffs were analyzed for pH, temperature, Electrical Conductivity (EC), Total Dissolved Solid (TDS), chromium (Cr), lead (Pb) and zinc (Zn). pH, temperature, EC, TDS were determined immediately in the sample. Analysis of the heavy metals was done using Flame Atomic Absorption Spectrophotometer. Data obtained were subjected to descriptive statistics, analysis of variance and means were separated using Least Significant Difference (LSD). All the physical and chemical properties investigated except pH, Cr and Pb decreased from the month of June to October. Cr and Pb were not detected in all the roofing sheets throughout the five months. Control had the least concentration of Zn throughout the months while galvanized metal sheets had the highest concentration. Zn concentration in the month of June ranged from 0.09 – 3.39 mg/l with coated pan having significantly (p < 0.05) higher Zn concentration. Provision of potable water to the entire population is necessary to avoid taken water contaminated with metals