The sources of groundwater pollution are closely related to human activities, and can be attributed to the following sources: Cities：Wastewater from households, broken underground pipelines and septic tanks, poorly-treated landfills, and hospitals which could cause infection might leak into the ground, causing groundwater pollution. Industries：Wastes produced during the manufacturing process, wastewater which contains toxic substances and heavy metals discharged from factories, and industrial manufacturing wastewater might all contaminate groundwater. Agriculture：Agricultural waste water that contains high salinity and inorganic substances, chemical residues, organisms from animal feces in the farms, germs or agents used for fertilization or soil improvement might as well contaminate groundwater. Others：Seawater intrusion, oil pipeline leakage, waste from ship breaking, chemical leakage from chemical factories, accidents involving vehicles transporting chemicals and/or toxic substances, waste from recreation areas might as well contaminate groundwater.