Glossary: Drinking Water Well Condition

These terms may help you make more accurate assessments when completing the Drinking Water Well Condition Fact/Worksheet. They may also help clarify some of the terms used.

Abandoned water well: A well which has been filled or plugged so that it is rendered unproductive and will prevent contamination of the ground water. A properly abandoned well will not produce water nor serve as a channel for movement through the well or between water bearing zones. Wells that are not used should be properly abandoned as soon as possible.


Air gap: An air space (open space) between the hose or faucet and water level. It is one way to prevent backflow of liquids into a well or water supply.


Anti-backflow (anti-backsiphoning) device: A check valve or other mechanical device to prevent unwanted reverse flow of liquids back down a water supply pipe into a well.


Aquifer: An underground formation of rock or sediments containing and capable of supplying ground water.


Backflow: The unwanted reverse flow of liquids in a piping system.


Backsiphonage: Backflow caused by formation of a vacuum in a water supply pipe.


Casing: Steel pipe installed while drilling a well, to prevent collapse of the well borehole, entrance of contaminants, and to allow placement of pumping equipment.


Cross-connection: A link or channel between pipes, wells, fixtures, or tanks carrying contaminated water and those carrying potable (safe for drinking) water. Contaminated water can enter the potable water system if it is under higher pressure.


Drilled wells: Any drilled excavation that is constructed with the intended use of diversion, artificial recharge, observation, monitoring, dewatering, or withdrawal of ground water.

Driven-point (sand point) wells: Wells that are constructed by driving assembled lengths of pipe into the ground with percussion equipment or by hand. These wells are usually small in diameter (two inches or less), less than 50 feet deep, and installed in areas of relatively loose soils, such as sand.


Dug wells: Large-diameter, relatively shallow wells lined with rock, brick, or concrete and often hand constructed. Typical dug wells are three to six feet in diameter and 15 to 50 feet deep.


Ground water: Subsurface water in soil, rock or sediment.


Grout: A fluid mixture of cement, bentonite, and water which is used to seal the space between the borehole and casing, or to properly fill and seal abandoned wells.

Milligrams per liter (mg/L): The weight of a substance measured in milligrams contained in one liter. It is equivalent to 1 part per million.