Groundwater enters the ground by virtue of gravity. It is found beneath the surface of the ground in the zone of saturation. Above the zone of saturation is the zone of aeration. As water enters the soil, it passes through the water table (area where much of the water is found) and into the zone of aeration where it is filtered by the soil and rock particles. The filtered water enters the zone of saturation where every pore space between rock and soil particles is saturated with water.