The saturated zone is the part of the Earth where all the spaces and fractures of rocks are filled with water. This water is referred to as "groundwater." Before soaking in, groundwater started as rain or snow.
The top of the saturated zone is called the "water table." This lies beneath the "unsaturated zone," where those spaces are primarily filled with air. Groundwater accounts for only about 1 percent of the world's water, but there is 35 times more water underground than in all the lakes and streams combined. Most of the ground water is located within 750 meters of the Earth's surface.