Agriculture can contaminate water with waste from animal feedlots or confinement areas and with agricultural chemicals such as plant nutrients and pesticides. Industry and municipalities contaminate groundwater with wastes, runoff and sewage disposal. Household septic systems can contaminate groundwater. Well water contamination can be caused by the sources listed above. However, well water may only be contaminated locally.
Contamination comes through the walls of the well.
Groundwater contamination implies a much larger land area as a contaminate source. People who work with groundwater quality usually use two broad terms to describe the origin of these sources of pollution. Examples include nitrates, which may originate from livestock, chemical fertilizers and natural occurrences in the soil. Copyright 1999 University of Missouri. Published by University Extension , University of Missouri-Columbia.