Abstract

Abstract: This paper examined the presence of coliform bacteria using the approaches of Most Probable Number (MPN) Index and Colony Forming Unit (CFUx105)in private wells and borehole in peri-urban areas of Makurdi, Benue State Nigeria. Water samples were collected during a one-year period from; Non-Cased Wells (NCW), Burn Brick Cased Wells (BBW), Concrete Cased Wells (CCW) and Boreholes (BH) in four locations; A, B, C and D during the wet and dry seasons and analysed for the presence of the colony groups. The samples were analysed using multiple tube fermentation methods and pour plate technique and the one-way analysis of variance (ANOVA) statistics was applied using Duncan’s new Multiple Range Test to separate the means where there was significant difference. The result revealed MPN index and coliform counts in all the wells in the various locations were above the World Health Organization (WHO) permissible limit for portable water. The MPN index was in the significant order (p ≤ 0.05) of NCW (32.77 %) > BBW (18.02 %) > CCW (14.78 %) > BH (3.95 %) in Locations: A (54.807) > B (42.679) > C (36.740) > D (30.943) respectively while the Coliform count was in the significant order (p ≤ 0.05) of NCW (72.42) > BBW (59.63) > CCW (49.05) > BH1(5.17) in Locations; A (57.963) > B (50.052) > C (46.432) > D (44.823) respectively. The MPN index and Coliform counts were significantly higher during the wet season than the dry (p ≤ 0.05). The study concludes that the water from these sources is unsafe for consumption except after dosing with appropriate germicides.

Key words: Coliform, Boreholes, Bacteria, Enterobacteriaceae, Contamination