Municipal solid waste disposal is a global concern, most especially in a developing nation like Nigeria where landfills are better categorized as open dumps, sited for convenience and usually involve the pitching of garbage into pre-existing holes. These open pits are located near residential housing, posing a threat to public health and the environment. Leachate, a high-strength wastewater, generated from the dumps poses a serious contamination risk to groundwater. This work was therefore done to assess the impacts of leachate percolation on groundwater quality and evaluate its toxicity using the African catfish. The occurrence of some conventional contaminants in some of the groundwater samples at concentrations above the World Health Organization (WHO) permissible limits for drinking water is a serious health concern. The results from the acute toxicity study reveal that the leachate is toxic and would be of assistance in the ecological risk assessment of landfills. The book calls for the stakeholders in solid waste management to make sustainable practices a high priority and construct well engineered landfills to ensure the protection of human health and the environment.