Assessment of Domestic Wastewater Disposal Practices and Groundwater Quality in Owerri, Imo State

This study assesses domestic wastewater disposal practices in Owerri, the capital of Imo State in South East Nigeria, and their impact on shallow groundwater quality in the densely populated urban environment. Owerri has grown rapidly without corresponding expansion of sewerage infrastructure, and the majority of households rely on pit latrines, soakaway pits, and direct greywater discharge to open drains, creating conditions for groundwater contamination. A combined survey and sampling approach was used: a questionnaire administered to 200 households collected data on wastewater disposal method, septic tank emptying frequency, and water supply source, while thirty groundwater samples from shallow hand-dug wells and boreholes were analysed for nitrate, ammonia, faecal coliform, total dissolved solids, and pH. Spatial analysis compared groundwater quality parameters against proximity to identified wastewater disposal points. Results indicate that nitrate concentrations in wells exceed the WHO guideline of 50 milligrams per litre in 13 of 30 samples, with the highest values near high-density residential areas where soakaway pit densities are greatest. Faecal coliform is detected in 17 of 30 samples, confirming microbiological groundwater contamination. Correlation analysis shows a statistically significant negative relationship between depth to water table and faecal coliform count, indicating vertical attenuation with depth. Households using boreholes below twenty metres depth show significantly lower contamination levels. The study recommends a sewerage master plan for Owerri and targeted deep borehole provision in high-risk zones. Keywords: groundwater contamination, domestic wastewater, sewage, Owerri, nitrate pollution.