COMPARATIVE ASSESSMENT OF THE POTABILITY OF ROOF-HARVESTED AND FREE FALL RAINWATER IN NJABA, IMO STATE

Abstract

The research compared quality of roof-harvested rainwater with quality of free fall rainwater in Njaba Local Government Area of Imo State with the aim of determining which of the two rainwater sources was suitable for drinking. A total of 32 sample points were utilized for collection of roof-harvested rainwater while 18 sample points were used for the free fall rainwater. Two samples, one for chemical analysis and the other for microbiological analysis, were collected at every sample location. Physical analyses were conducted in-situ while chemical and microbiological analyses were carried out in the laboratory. The following parameters were analyzed: pH, electrical conductivity, Cd, Cu, Mn, Zn, Pb, Cr, NO3-, PO43-, Cl-, E-coli, and total coliforms. The analysis results were compared with the WHO drinking water quality standard so as to determine whether any of the tested parameters exceeded the permissible limits established in drinking water. Similarly, water quality indexing technique was utilized to further evaluate the suitability or otherwise of the collected rainwater for drinking. Statistical analysis was carried out by means of one-way analysis of variance (ANOVA) and this helped elucidate statistically whether there was any significant difference between the qualities of free fall and roof-harvested rainwater. The results showed that in terms of the physicochemical parameters, free fall and rooftop harvested rainwater were generally of good quality and can be used for potable purposes. Furthermore, most of the free fall rainwater showed microbiological counts that were within the maximum permissible limits for drinking water. This implies that microbiological pathogens do not have much positive impacts on free fall rainwater. In contrast, the microbiological quality of roof-harvested rainwater was generally bad as most of the analyzed samples showed total coliform and E. coli counts that were above normal. The result of statistical analysis showed that there was a significant difference between the water quality of free fall rainwater and that of roof-harvested rainwater.