People have long relied on aquifers as the source of high-quality water. Today, about half of the American population uses ground water for its domestic needs. More than 89 percent of public water supply systems draw some or all of their drinking water from sources found underground in rock, sand, and gravel aquifers. In the arid areas of the country, aquifers are often the only source of water available. With increased use of water by industry, homes, and municipalities, our national reliance on ground water is expected to increase.
Ground water is a vital link in the water cycle.
Ground water feeds rivers, lakes, and streams used for drinking water. Aquifers are replenished by rainfall or other surface water percolating through the soil. In turn, ground water supplies the base flow of many streams and feeds lakes through underground springs. Ground water can move across state boundaries. It continually moves, sometimes recharging surface waters miles from where it started.