Groundwater is the water that is in the cracks and spaces between sand, soil and rock underground, and it sometimes bubbles up to the surface through springs. It is naturally replenished by rain and melting snow that seeps into the ground, and in turn, replenishes rivers, lakes and wetlands.
More than 50 percent of the people living in the United States depend on groundwater for drinking, including most of the people who live in rural areas. The bulk of groundwater is used for irrigation for growing food crops. Many areas of the world face water shortages because the groundwater is not naturally replenished as fast as it is used.