Aquifer

A natural underground layer, often of sand or gravel, that contains water.

Ground Water

The water that systems pump and treat from aquifers (natural reservoirs below the earth’s surface).

Raw Water

Water in its natural state, ground water or surface water, prior to any treatment for drinking. 

Sole Source Aquifer

An aquifer that supplies fifty percent or more of the drinking water of an area.

Source Water

Water in its natural state, prior to any treatment for drinking. See finished water.

Surface Water

The water that systems pump and treat from sources open to the atmosphere, such as rivers, lakes, and reservoirs.

Water Shed

The land area from which water drains into a stream, river, or reservoir.