Groundwater pollution, also called groundwater contamination, is the entry and spreading of harmful substances into groundwater, including inorganic chemicals, organic chemicals, microorganisms and radioactive substances. It is reducing the amount of fresh water available for household use, agriculture, industrial applications and other purposes and harming public health through poisoning and the spread of water-borne diseases.
Some groundwater has always been polluted with natural substances and as a result of natural processes. Particularly common natural sources are mineral deposits containing arsenic and fluorine. Others include salt, iron, manganese, chromium, radon and uranium.
However, the extent and severity of groundwater pollution worldwide has increased greatly during the past century or so, together with increasingly severe groundwater depletion, both as a result of human activity. Major sources of such human-caused pollution include leakage from sewers, the use of chemical fertilizers, fracking, leakage from gasoline stations, effluent from wastewater treatment plants, leakage from landfills and discharges from industrial processes.