There are various different sources of groundwater pollution or contamination in the United States as well as other problems of water use . Pollution can be divided into point source (as when there is a specific source such as a leaking holding tank) and non-point source (acid rain contaminating ground water) contamination.
The first major source of problems is agriculture. Products such as fertilizers and pesticides used in agriculture can contaminate ground water. Agriculture is also a use problem in that artificially inexpensive water for agriculture has led to depletion of rivers and aquifers.
Another issue is industrial pollution. This can involve both chemical waste and thermal waste – i.e. when water used for cooling is returned to rivers and the higher temperature kills fish.
Urban run-off is another major source of water pollution. Cities use lots of water and concrete prevents reabsorption of water back into aquifers.