Physico-Chemical Changes and Bacteriological Deterioration of Potable Water During Long Term Storage

Abstract

Potable water samples obtained from near the treatment plant were analysed for some physical and chemical parameters as well as changes in microbial population during storage. Although values obtained for pH, total acidity, total alkalinity, and total hardness of water samples decreased with duration of storage, recorded values were still within FAO recommended standards for drinking water. Suspended particles became noticeable and the smell of water samples became unpleasant after 12 weeks of storage. Escherichia coli, Enterobacter aerogenes, Staphylococcus aureus, Pseudomonas aeroginosa, Klebsiella pneumoniae Proteus sp. Streptococcus faecalis and Micrococcus sp were the bacteria species encountered in stored water samples. E. coli was the most frequently encountered. The presence of these bacterial species has significant health implications. Total viable counts in water samples increased from 3.8 x 10⁵ cfu/ml on day 0 to 42.0 x 10⁵ cfu/ml by the  16^th week of storage, while coliforms increased drastically from week two to week six of storage after which the population began to drop. Differences between control and stored water samples were significant (p<0.05) in all cases considered. That treated water samples entering the distribution system samples contained  coliforms cast a doubt over the potability status of water supplied to the communities in the area under study.