Common well terminology
Public water supplies v. private well water
NC private well resources
Well constructionWells are constructed to capture water that is underground for drinking or other purposes. Wells typically consist of a pipe that connects an aboveground cap, or wellhead, to an aquifer. An aquifer is an underground formation that contains water. The well then uses a pump to draw the water from the aquifer and deliver it to a house or outdoor faucet. The picture on the right shows typical well construction in more detail.
Wells can be constructed in a variety of ways, including dug, driven, or drilled, depending upon the underlying geology of the land, the depth of the aquifer, and the available resources of the well driller.1 At present, few wells are hand dug; most are drilled by a truck-mounted drill rig.2
The construction of wells varies across the state. In some places, such as the coastal region of North Carolina along the Outer Banks from Nags Head to Ocracoke Inlet, the only potable (suitable for drinking) water is 10-20 feet below the surface of the land. In other areas such as the NC Slate Belt in Stanly, Union, and Montgomery counties, wells must be "cased to a minimum depth of 35 feet."3 Throughout the rest of North Carolina, wells must be cased to a minimum of 20 feet, but many are more than 100 feet deep. Well depth can vary considerably even within regions and counties since each well must be drilled to reach the aquifer in that particular location.
Drinking Water from Household Wells
Aquifer- An underground formation or group of formations in rocks and soils containing enough ground water to supply wells and springs.1
Water table- The top of the saturated soil or rock in an aquifer. When the aquifer recharges, the water table rises, then gradually drops as the water is removed or used.1
Well casing- The tubular lining of a well. Also a steel or plastic pipe installed during construction to prevent collapse of the well hole.1
Wellhead/ well cap - The top of a structure built over a well. Wellheads are important for preventing surface contamination from entering underground water supplies or from items or animals falling into the well tube.1
Fact sheet about NC private well water.
er supplies are routinely monitored for impurities and are regulated by the federal government and water utilities. Most public water supplies derive their water from groundwater, lakes, rivers, and reservoirs where it is pumped to a water treatment plant for purification before it is delivered to homes and businesses as drinking water. The Safe Drinking Water Act and other regulatory acts protect large drinking water supplies, watersheds, and reservoirs that contribute to the public drinking water supply. The Safe Drinking Water Act does not, however, enforce monitoring of private well water quality.4
Since 2008, all new private wells in North Carolina must be tested for inorganic and bacterial contaminants. Once the well is certified, testing the private well water is solely the responsibility of the well owner. Although most well water is safe to drink, wells must be regularly monitored to ensure that if contamination occurs, it is identified early.5 Some drinking water contaminants are harmful to human health but do not cause any noticeable changes to the taste, smell, or color of the water.5 The absence of any unpleasant changes to the water means that if the drinking water is not regularly tested, it may be contaminated for many years before the problem is discovered.
Follow these links to find out more about private well water in North Carolina and state programs for monitoring well water quality.
North Carolina Department of Environment and Natural Resources Private Wells Branch.
National Ground Water Association: information about groundwater usage in North Carolina.
|Last updated January 15, 2013|