Bacteriological Analysis Of Water Tanks

Good quality drinking water can be polluted in many several ways of which faecal and soil pollution are the most important with respect to microbial agents. The aim of the study was to assess the contamination status of drinking water stored in water tanks in residence of Varitas University. Questionnaires were administered to residents to obtain information about the poly tanks and the usage of water from the tanks by users. Samples of the water tank were collected aseptically and 100 ml filtered through sterile membrane filters with 47 mm diameter and 0.45 µm pore size obtained from Merck Millipore. The membrane filters were aseptically placed on prepared sterile agar plates including, Harlequin agar for total coliforms and Escherichia coli, media-faecal coliforms (m-FC) for faecal coliforms, and plate count agar for total viable counts, respectively. The inoculated Harlequin and plate count agar plates were incubated at 37° for 24 h whiles the inoculated m-FC plate was also incubated at 44° for 24 h. From the questionnaires administered, 26% of the study participants said they use the water in the tank for drinking, 70% uses it for cooking, whiles all use it for bathing, and washing purposes. Mean counts of the indicator bacteria in the household storage water tanks ranged 2.5-3.5 log10 CFU/100 ml for total viable count, 2.3-3.2 log10 CFU/100 ml for total coliforms, 2.1-2.6 log10 CFU/100 ml for E. coli, and 0.5-2.9 log10 CFU/100 ml for faecal coliforms. From the study all the selected household storage water tanks were contaminated with faecal indicator bacteria including faecal coliforms and E. coli above the recommended World Health Organization (WHO) standards of concentration of faecal coliforms must be zero in safe drinking water. However, further studies are also recommended to be done to understand the effect of type of water storage tank (i.e.plastic, concrete, etc) on the water contamination.