Groundwater pollution due to human activities (agricultural practices, industrial development, urbanization, etc.) and natural sources primarily takes place through leaching, infiltration, and direct discharge. Toxic chemicals, heavy metal, and organic substances generated through various activities migrate to underlying aquifers through soil. Nitrates (NO3−) in plentiful amounts make passage to groundwater resources when indiscriminate applications of chemical fertilizers are carried out. Pharmaceutical residues, hormones, and parasites in livestock wastes may also contaminate groundwater. In some areas, wastewater or even effluents from an industry are used to utilize for recharging of aquifers. Industries generate a wide range of pollutants: heavy metals, toxic chemicals, solvents, volatile organic compounds (VOCs), oils, grease, pharmaceuticals, hormones, etc., which contaminate groundwater sources. Leaching of heavy metals and other contaminants and cyanides during gold mining and acid mine drainage (AMD) are the main pathways to groundwater contamination through mining operations. Landfill leachate (LFL) remains a significant environmental threat because of the toxic pollutants that can be the ingredients of groundwater pollution. The leaked petroleum products seep into groundwater resources and pollute water with dangerous BTEX (benzene, toluene, ethylbenzene, and xylene) compounds. Urbanization at a very rapid pace has generated numerous environmental crises including groundwater scarcity and pollution. The natural sources of groundwater pollution include geologic contaminants, saline intrusion, radioactive contaminants, natural organic matter (NOM), and metal leaching, etc. Arsenic poisoning in Bangladesh, excesses of fluoride in groundwater in many places in India, salt water intrusion in Nile Delta aquifer, and ten times higher uranium concentrations than the WHO’s guidelines in Ireland are some of the dismal scenarios emerged out of the state of groundwater pollution beyond tolerable limits.