Effects of Storage/Biofilm Formation on Physico-chemical and Bacteriological Qualities of Potable Water Supply in Benin City

Abstract

Deterioration of water quality during storage and in distribution system remain one of the major difficulties experienced by the potable water suppliers. This study examined the effects of storage/biofilm formation on physico-chemical and bacteriological qualities of potable water supplies in Benin City. In the course of this study, twelve (12) water samples (three bottled water samples, three borehole water samples, three sachet water samples and three tap-water samples) were collected within Benin City metropolis, Edo state, Nigeria. The water samples were stored for six (6) weeks at ambient temperature and then analyzed weekly for bacteriological and physico-chemical qualities. Nutrient agar and Macconkey agar media were employed in culturing of isolates from water samples using standard methods. Total viable bacterial counts increased with storage in all forms of potable water samples analyzed while total coliform which appeared on first week in borehole and tap-water samples was observed in fourth week in sachet water samples. pH, temperature and dissolved oxygen decreased in all forms of potable water samples within six (06) weeks of storage while phosphate value increased throughout the duration of storage. Total bacterial counts obtained from the various water samples indicated that bottled water, borehole water, tap water and sachet water had counts ranging from 2.8 x 10 2 - 3.1 x 10 3 cfu/ml, 1.5 x 10 2 - 4.1 x 10 3 cfu/ml, 1.3 x 10 2 - 3.9 10 3 cfu/ml and 1.0 x 10 2 – 3.0 x 10 3 cfu/ml respectively. Morphological and biochemical tests performed on isolates from water samples revealed the presence of Klebsiella sp. Bacillus subtilus, Pseudomonas aerugimosa Enterobacter aerogenes, Staphylococcus aureus .