Water which seeps into the ground passes through
a zone of aeration where the open spaces between soil particles
are filled with both air and water. We cannot pump water from this
zone. Below the zone of aeration lies the zone of saturation where
all of the spaces between soil particles are filled with water.
The water in this zone is called groundwater and is available for
pumping. An aquifer is made up of all the soil, rock and water
in the zone of saturation. The dividing line between the two zones
is called the water table. Groundwater moves through the subsurface
supplying streams and lakes.