Groundwater remediation is the process by which water pollution is extracted and filtered. Groundwater is a readily available source of drinking water. At least one half of the population of the United States depends upon groundwater as a source of drinking water. Groundwater is also used by farms to irrigate crops and by industries to produce everyday goods. Most groundwater is clean, but groundwater can become polluted, or contaminated as a result of human activities. The many and diverse activities of man produce innumerable waste materials and by-products; these are often deposited or stored on land surfaces where by percolation they eventually get carried downward contaminating the underlying groundwater and therefore jeopardizing the natural quality of it. As a result, contaminated groundwater becomes unsuitable for use. Using contaminated ground water causes hazards to public health through poisoning or the spread of disease. Contaminants found in ground water cover the entire range of physical, inorganic chemical, organic chemical, bacteriological, and radioactive parameters. Pollutants and contaminants can be removed from ground water by applying various techniques thereby making it safe for use.

http://en.wikipedia.org/wiki/Groundwater_remediation