Groundwater is an underground resource which comes from surface water (primarily rain and melting snow) that infiltrates the earth through the cracks and open spaces in rocks and soil.  Saturated layers below the “water table” that store and transmit significant quantities of groundwater are called aquifers.

About half of our nation’s drinking water comes from groundwater most of which is through public supply wells.  In suburban and rural areas many families receive their fresh water from private wells.

A “watershed” is the land area where water soaks through the earth recharging the aquifer or saturated zone. The water table is the line below which the ground is saturated with groundwater and available for pumping.  During dry seasons it is common for the water table to drop.

Keeping groundwater clean from surface contaminates is critical and is everyone’s responsibility.  Fuel spills, underground storage tanks, poorly constructed or deteriorating wells are all potential routes of groundwater contamination. 

GROUNDWATER USE IN ILLINOIS

• 49% of the population regularly use groundwater for their drinking supply
• 1,500,000 residents are served by private wells
• 4,229,365 residents are served by community water wells
• Major Illinois Users:

Public supply – 353 Mgal/d

Individual households – 135 Mgal/d

Irrigation – 150 Mgal/d

Livestock/Aquaculture – 37.6 Mgal/d

Industrial (self-supplied) – 132 Mgal/d

Mining – n/a

(Mgal/d – millions of gallons per day; data from the National Ground Water Association)