Quality Assessment of Some Groundwater Samples in Ogbomoso Metropolis, Southwest Nigeria

Abstract

This study examines the physico-chemical and microbiological attributes of water samples obtained from ten boreholes that were sampled twice a month for a period of five months. The physico-chemical attributes revealed that the ammonia, manganese, nitrate, nitrite, fluoride, chloride contents, conductivity and total dissolved solids were below the permissible levels. However, total alkalinity and total hardness values of some water samples were higher than the permissible levels, while all the water samples had BOD and COD values that were higher than the permissible levels. The pH of water samples ranged from 5.8-6.9, showing that only two samples fell within the permissible levels. Similarly, the temperature ranged from 31.5-35.4 ^oC, with only two samples having values that fell within the permissible levels. The microbial quality of the water samples indicates extensive microbial contamination involving heterotrophic bacteria, coliforms, yeasts/molds, staphylococci, and Shigella. However, Salmonella was not isolated in this study. Bacterial isolates such as Proteus, Escherichia, Shigella, Streptococcus, Staphylococcus, Bacillus, Pseudomonas, Enterobacter, and Klebsiella with multiple-drug resistance ranging from 2-8 were encountered. The safety of the borehole water can be enhanced through regular cleaning, disinfection of storage tanks and further treatment by end-users to ensure the potability of water. This study provides baseline data with regard to the quality of underground water within Ogbomoso metropolis, Nigeria.

Keywords: ground water, boreholes, microbiology, physico-chemical attributes, antibiotic resistance