Groundwater
Groundwater is water that exists in the pore spaces and fractures in rock and sediment beneath the
Earth's surface. It originates as rainfall or snow, and then moves through the soil into the
groundwater system, where it eventually makes its way back to surface streams, lakes, or oceans.
Groundwater makes up about 1% of the water on Earth (most water is in oceans).
But, groundwater makes up about 35 times the amount of water in lakes and streams.
Groundwater occurs everywhere beneath the Earth's surface, but is usually restricted to depths less that about 750 meters.
The volume of groundwater is a equivalent to a 55 meter thick layer spread out over the entire surface of the Earth.
The surface below which all rocks are saturated with groundwater is the water table.