Salt in water

Every natural water supply contains some sodium, with concentration depending upon the exposure of the water to soluble compounds which are present in the earth or in the atmosphere.

The natural contamination of fresh ground water by saltwater is an important water-quality issue in many areas of Illinois. This saltwater comes from naturally occurring salt minerals in the subsurface. Proper management of ground water reduces, and frequently avoids, intrusion of saltwater into freshwater supplies.