Variation of rain water quality with storage time for different coloured storage containers

It is very important to evaluate the quality of rain water collected and stored in cisterns and storage tanks. In this study, rainwater quality analysis was carried out on samples collected from an experimental set -up at the School of Engineering and Engineering Technology of the Federal University of Technology, Akure, Nigeria. The physio-chemical and bacteriological characteristics of rainwater collected and stored using four different coloured containers under outdoor and indoor conditions were analyzed and the results compared with World Health Organization (WHO) standard for potable water. The results of the physio-chemical analysis revealed that the colour, turbidity, total dissolved solids (TDS), phosphate, sulphate, iron and copper of all the rainwater samples fell within WHO acceptable standards for potable water. The pH of the harvested rainwater of the samples ranged from 5.34 – 6.73 mg/l for the indoor stored rainwater samples and 5.28 – 6.59 mg/l for the outdoor stored samples. The pH of the water samples did not fall with WHO permissible limit of 6.5 to 8.5. The Nitrate content of the water samples also did not fall within WHO permissible limit. Similarly, the total coliform count did not conform to WHO standard for potable water. Based on the results obtained from this study, it is recommended that harvested rainwater be treated to kill contaminating microorganisms and to reduce the health risks associated with its consumption.