Water Quality Index (WQI) model was utilised to evaluate the physicochemical parameters of groundwater quality at the effluent discharge and administration areas of a waste treatment facility (WTF) in Shama Municipality in Ghana. Borehole water samples were collected once a week for six months and coliform bacteria were determined in the samples using Colony Forming Unit while the physicochemical parameters were analysed using instrumental and titrimetric techniques. Twenty physicochemical parameters were used in computing the WQI of groundwater. Groundwater collected I km away and within the WTF tested negative and positive for coliform bacteria respectively. WQI classified groundwater samples collected at the effluent discharge area as poor water quality type. However, groundwater collected 1 km away and at the administration area of the treatment facility was of good physicochemical quality. The levels of EC, COD, TDS, Ca2+, Mg2+and Cl− ions exceeded the WHO drinking water permissible limits. Statistically, there was no significant difference between mean levels of physicochemical parameters of groundwater at the three locations (p < 0.05). PCA revealed that weathering and dissolution of rock minerals and human-induced activities negatively affected the groundwater quality. The WTF groundwater was unsafe for use. Aquifer development and artificial recharge for sustainable development are recommended.