Empirical analysis of the impact of urbanization on groundwater quality within the slums of Accra, Ghana

A significant proportion of city dwellers in Ghana reside in slums where groundwater is the major source of water for domestic uses. This study examined the quality of groundwater from boreholes (seven) and hand-dug wells (13) in five major slums in the city of Accra, Ghana. Water samples were tested for a total of 27 microbial and physicochemical contaminants at the central laboratory of the Ghana Water Company Limited. Overall, the water quality in the slums was poor as most of the parameters tested did not meet the 2017 WHO standards. Four out of the five slums (in Nima, Chorkor, Jamestown, and Abokobi-Pantang), for instance, recorded high amounts of lead, with average values of 0.25 mg/L, 1.00 mg/L, 0.25 mg/L, and 1.5 mg/L, respectively, which are above the WHO standard of 0.01 mg/L. pH values in Nima (5.09), Sabon Zongo, Chorkor (6.09), and Abokobi-Pantang (6.17) did not meet the WHO standard of 6.5–8.5. All five slums indicated various degrees of bacteriological contamination. The average Escherichia coli values per slum ranged between 12.50 CFU/100 ml and 249.00 CFU/100 ml, while the mean total coliform per slum ranged from 90.75 CFU/100 ml to 490.25 CFU/100 ml. The poor quality of groundwater found is attributable to improper disposal of waste, siting of boreholes/wells close to toilets, and the coastal location of some of the slums. Strict enforcement of water-quality control checks, intensive sensitization on the dangers of improper waste disposal to groundwater quality, and the provision of sanitation facilities in the slums by city authorities are highly recommended.