The United States uses 76.4 billion gallons per day of fresh ground water for public supply, private supply, irrigation, livestock, manufacturing, mining, thermoelectric power, and other purposes. Ground water is tapped through wells placed in water-bearing soils and rocks beneath the surface of the earth. More than 15.9 million water wells supply the United States with 76.4 billion gallons of fresh ground water each day. Approximately 800,000 boreholes are drilled in the U.S. annually. The construction of these vitally needed water supply systems involves the use of more than 19,000 drilling rigs by an estimated 8,000 ground water contracting firms.
Ground water is a renewable resource.
In most parts of the country, water removed from the ground is constantly replaced, although in some parts of the country such as arid and semi-arid regions, a low rate of replenishment is far exceeded by the rate of ground water pumping, resulting in serious problems of ground water mining. Ground water accounts for 35 percent of all the water used by U.S. municipalities. Some 49 billion gallons of ground water are used daily for agricultural irrigation from more than 516,000 wells. In 1900, the U.S. used only 2.2 billion gallons of ground water daily for irrigation from 17,000 wells. California leads the nation in the number of irrigation wells with 71,554.