Carroll County Map and Logo
Larry L. Leitch, M.A.,M.P.A.
Health Officer
Henry G. Taylor,M.D.,M.P.H
Deputy Health Officer
[end cap]
Carroll County Health Department - Carroll County Maryland
Snapshot of Building
Water Quality - Definition of Water/Well Terms

Definition of Water/Well Terms
  • Annular Space: The space between the outside of the well casing and the bore hole. Failure to properly seal this space with grout can cause well contamination.
  • Aquifer: Any formation of soil, sand, rock, gravel, limestone, sandstone, or other material, or any crevice from which undergound water is or may be produced.
  • Casing: The material that is used to keep the upper portion of the well stable. Casing must be either steel or PVC plastic and must be at least 20 feet into the ground.
  • Contaminant: Any physical, biological, chemical, or radioactive substance in drinking water.
  • Cross-Connection: A faulty plumbing connection that allows contaminated water to enter a water supply pipe.
  • Coliform Bacteria: A group of bacteria that, if present in water, show that other pathogens may exist. Coliform bacteria are indicator organisms and are not harmful themselves.
  • Chlorinator: A device used for the injection of chlorine into drinking water for the purpose of disinfection.
  • Conduit: Tube from which wiring from well pump exits well casing and goes underground. Conduit must be securely sealed to well cap.
  • Dug Well: A dug well is a well that is usually excavated by hand. Dug wells are very susceptible to contamination.
  • Fracture: Opening or crack in underground formation through which water flows and enters the well.
  • Grouting: Material that is placed in the annular space of the well during well construction. Grout is normally composed of Portland cement; however, bentonite clay is used in certain applications such as monitoring wells.
  • Ion Exchange: Method of treating water for the removal of nitrates. Water is passed through bed of resin and ions are exchanged between the water and the resin.
  • Nitrates: Final product of the oxidation of ammonia. Sources include septic systems, fertilizer, manure, etc. Nitrates can cause methemoglobinemia or "blue babies" by not allowing hemoglobin (the blood pigment) to transport oxygen. Nitrate levels in drinking water should not exceed 10 mg/l (ppm).
  • Nitrites: First product of the oxidation of ammonia.
  • Permeability: The capability of a formation to transmit water.
  • Pitless Adaptor: Unit through which the water line exits the well casing and goes underground towards the building. Unit must be at least 42" below the ground surface. The pitless adaptor is evaluated at the time of well final inspections.
  • Pollution: Any contamination or other alteration of the chemical, physical or biological properties or water.
  • Potable Water: Water that is free from impurities in amounts sufficient to cause disease or harmful physiological effects.
  • Pressure Tank: Tank that is used to ensure consistent water pressure and for storage of water. Usually located in basement of house but sometimes (in older settings) located in well pit.
  • Reverse Osmosis: Method used for the treatment of water to remove nitrates. This method uses a membrane which separates treated water from waste.
  • Sediment Filter: Filter used to remove particulates from water. Often required as pre-treatment for other types of treatment such as ultraviolet disinfection.
  • Ultraviolet Disinfection: Method of treatment to remove bacteriological contamination from water. Less maintenance required than chlorination, however, initial cost is more than chlorination. Unit should be installed with proper controls (fail-safe device, meter, no by-pass of unit). See disinfection devices.
  • Well: Any hole made in the ground to explore for ground water, to obtain or monitor ground water, or to inject water into any underground formation from which ground water may be produced.
  • Well Cap: Device placed on top of well casing to protect water supply from outside sources of contamination. All new wells in Carroll County are required to use 2-piece sealed and vented style caps. It should be noted that the vented portion of the cap (where the screen is) must be left intact for the cap to retain its integrity. It is improper to allow anything such as the rope connected to the well pump to exit the well casing through the vent hole.
  • Yield Test: Required of all new wells. Domestic wells must be capable of producing at least 1 gallon per minute. Also, at least once a day, the well must be able to produce 500 gallons in a 2-hour period. Well storage and tank storage is taken into consideration for this requirement. A well yield test must be conducted for a minimum of 3 hours. If after 3 hours, the well has consistently yielded 4 gallons per minute or more, the test may be terminated. If a well yields under 4 gallons, it must be yield tested for a minimum of 6 hours.

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