Determination of hand-dug well conditions and groundwater quality in Ifo area of Ogun State, Nigeria

Abstract

Background/Aim: Inadequate provision of public water for domestic uses has led to private house-owner to explore shallow water-well in Nigeria. While many of these wells are not constructed following standard procedure, the water quality is hardly determined in the laboratory. This research assessed the condition and water quality of hand-dug wells of a semi-urban area in Ogun State, Nigeria. Methods: Eleven sites were selected using stratified-random sampling method and a total of 110 wells were subjected to a standard checklist modified from swoveland. Ten water samples each from wells with high and low risk scores were collected in triplicates. Sixty samples in total were analysed for chemical parameters using flame photometer and UV/Visible Spectrophotometer while Total Bacteria and Coliform count were estimated using pour-plate technique.Results: The checklist evaluation of well characteristics showed that between 10 and 69 % of sampled wells were sited less than 2, 5 and 15 m from dwelling units, outdoor premises and sewer pipes/septic tanks respectively. It also revealed that well casing was present in about 62 % of the wells. Mean concentrations of Total Dissolved Solids (35.00±2.00 - 975.00±15.00 mg/L) and Total Hardness (3.20±0.45 - 399.05±383.41 mg/L) exceeded the permissible limits of WHO while K+ (50.24±30.11 - 0.05±0.05 mg/L), Na+ (2.87±0.14 - 152.56±12.51 mg/L), Cl- (28.80±0.00 - 244.80±7.20 mg/L), SO42- (1.00±1.00 - 1.33±0.58 mg/L) and NO3- (0.11±0.04 - 13.07±5.72 mg/L) were within the limits. The microbial load in the water samples ranged from 3.2x106 - 12.3x106 CFU/ml for bacteria count and 1.7x106 - 12.5x106 CFU/ml for coliform count.Conclusion: There were significant correlations between the well risk scores and water parameters. Well owner’s knowledge about standards for well constitute an intense factor in the determination of well-water quality. Therefore, the area of the wells should be protected in order to minimize contamination from sources of pollution.