Groundwater contamination in Nigeria poses significant challenges to public health and ecological integrity. This review chapter unveils the reality of groundwater contamination in Nigeria, a nation grappling with rapid industrialization and urbanization. Comparative analysis reveal that contaminant sources, such as agricultural activities, industrial discharges, urbanization, waste disposal practices, hydrocarbon extraction, mining operations, and natural sources, are all contributing to the poisoning of groundwater resources. The implications on the health systems and ecological risks associated with these contaminants and mitigation strategies were discussed. The Niger Delta, a region rich in oil, suffers from hydrocarbon contamination, with petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAHs) levels exceeding European Union limits, while agricultural regions like Kano and Kaduna are battling high nitrate levels from excessive fertilizer use. The geophysical, geochemical, and hydrochemical data expose elevated levels of contaminants, unveiling toxic heavy metals, petroleum hydrocarbons, and hazardous chemicals infiltrating soils, groundwater, and surface water bodies, endangering ecosystems and public health. This contamination is not just an environmental challenge; it is also a public health emergency, leading to a surge in dangerous waterborne diseases like typhoid and cholera. The economic consequences are equally devastating. The cost of treating contaminated water, coupled with the rising healthcare burden from waterborne diseases, places a significant strain on households and burdens the national economy. Contaminated irrigation water leads to crop failure, impacting food security and livelihoods, and further exacerbating poverty. The social impact of groundwater contamination is profound, as communities in contaminated areas often exhibit remarkable resilience, developing innovative water purification methods. However, the unequal distribution of resources and access to clean water can exacerbate existing social inequalities, leading to tensions and conflict. This chapter underscores the urgent need for a multi-pronged approach to address this crisis. Strengthening regulations, promoting awareness, investing in infrastructure, and innovative research are crucial steps toward safeguarding the Earth’s most precious resource.