This PowerPoint file contains information about ground water basics. The slide show

includes information about what ground water is, how much of it there is, how much we use, where it comes from, where it goes,

and how we use it.

Ground water is an important part of the water cycle

United States Geological Survey (http://ga.water.usgs.gov/edu/watercycle.html)

Ground water is the water in saturated pores of soil or rock. The point separating the saturated and unsaturated soil or rock is called the water table.

watertable

United States Geological Survey (http://ga.water.usgs.gov/edu/waterdistribution.html)

About 1% of the earth’s total water and 22% of the earth’s fresh water occurs as ground water

Ground water is important because 75% of us get our drinking water from ground water. Lakes and

rivers also get a lot of their water from ground water

EPA (http://www.epa.gov/seahome/gr

oundwater/src/geo.htm)

EPA Region 2 (http://www.epa.gov/region2/water/grndtop.htm)

Ground water starts as rain, melted snow, or water from a lake, river or wetland that percolates (seeps)

through the soil

Pennsylvania League of Women’s Voters – Water Resources Education Network (http://pa.lwv.org/wren/pubs/primer.html)

An aquifer is a geologic formation that yields a useable amount of water. A confining layer does not

yield water fast enough to be used.

EPA (http://www.epa.gov/seahome/groundwater/src/geo.htm)

An unconfined aquifer has no confining unit separating it from the land surface. The water level in a well rises to the

top of the aquifer. A confined aquifer has one or more confining units above it. Water in a confined aquifer is under pressure and the water level in a well rises above the aquifer.

EPA (http://www.epa.gov/seahome/groundwater/src/geo.htm)

Aquifers may consist of sand and gravel, limestone that is fractured or partly dissolved, or sandstone that is fractured. Clay, shale and crystalline rocks

are usually confining materials.

Pennsylvania League of Women’s Voters – Water Resources Education Network (http://pa.lwv.org/wren/pubs/primer.html)

Ground water flows from high to low elevations. Areas of high elevation are recharge areas.

Pennsylvania League of Women’s Voters – Water Resources Education Network (http://pa.lwv.org/wren/pubs/primer.html)

Ground water flows very slow. For example, water in a river flows about 1000 to 10000 times faster than

in an aquifer, and a billion times faster than in a confining material

0.00001

0.001

0.1

10

1000

100000

10000000

River Limestone Sand Clay

Feet

per

day

Ground water flows towards and discharges to rivers, lakes, wetlands, springs, or wells.

United States Geological Survey (http://ga.water.usgs.gov/edu/earthgwdecline.html)

In this diagram,

ground water discharges to a

well and a stream

We get ground water from a well. A well is a pipe that is drilled down into an aquifer. We

get the water out of the well with a pump.United States Geological Survey

(http://ga.water.usgs.gov/edu/earthgwwells.html)

A 2 inch diameter well is being driven on the left with a drill rig. Wells can also be drilled or dug (above). The

pump on the left is placed below the water level and pushes water up the well.

Additional Sources of Information

• http://www.epa.gov/seahome/groundwater/src/ground.htm

• http://pa.lwv.org/wren/pubs/primer.html• http://www.issaquah.org/COMORG/gwac/

Hydro.htm• http://www.extension.umn.edu/distribution/

naturalresources/DD5867.html