ABSTRACT

This study was carried out to determine the effects of different roof catchments on the quality of rainwater for domestic consumption in Umuahia Metropolis. The objectives of this study was to determine the physical, chemical and microbial quality of rainwater from rooftops and as such determine the roofing material and rainfall stage most suitable for rainwater harvesting. The overall water resources were assessed by the application of water quality index (WQI). Analysis of physiochemical properties and heavy metal concentrations in sampled rainwater were subjected to ANOVA among the roofing materials and the mean differences were separated using Duncan Multiple Range Test. The level of pollution between the sampled rainwater was made comparing the results of the physicochemical parameters to WHO and FMEnv for portable uses. This was summarized by the use of correlation coefficient while regression was used to determine the dependency of other parameters on pH. T-test was used to compare the means of the physiochemical parameters amongst the different rainfall periods. The result showed that the pH content of the harvested rainwater ranged from 6.20 – 6.90 in all the months while the acidity of the harvested rainwater samples were significantly higher (p ≤ 0.05) than that of the control. However, all the values obtained for the physiochemical properties fell within the WHO &FMEnv permissible limit. Notably, Lead was detected only in Asbestos during the month of April and whereas. Zinc was detected in the 3 rainfall periods (months) with the highest value recorded in April in SRC3 (4.35mg/l) which was above the permissible limit of WHO (3.0mg/l) but within FMEnv limit (5.0mg/l). From the calculation of WQI, all roof catchments in all the months exceeded the critical value of 1.0 used to judge unpolluted water and therefore should be subjected to treatment for portable purposes.  A good amount of bacteria was also detected in all the samples but rainwater from asbestos in April had the highest amount of coliform 3.4 X 103. From the result of this study, rainwater from these roof catchments could serve for domestic consumption. The month of July showed to be the most suitable period for rainwater harvesting while SRC4 (Harvey-tiles) proved to be the most suitable roof catchment for rainwater harvesting, followed by SRC2 (Aluminum rooftop). However, it is advised to subject rainwater from roof catchments to further treatments especially if it must be used for portable uses like drinking.