Well Anatomy

Maryland has established guidelines for the construction of wells. All wells must be constructed by licensed well drillers in accordance with State regulations. The well must pass inspection and the water must be certified as potable (drinkable) by the County Health Department before the well can be used. [Maryland Health Departments numbers and addresses.] The following components of a typical domestic well are illustrated on the accompanying figure.

CASING: A metal or plastic pipe used to line a portion of the bore hole. The minimum length (depth) of the casing is determined by State regulations based on the geology of the area. The casing must extend a minimum of 8 inches above the ground (24 inches in flood zones) to keep storm water runoff out of the well.

GROUT: Material used to provide a watertight seal between the bore hole and the casing to prevent surface water and contaminants from running down the side of the well. Grouting may be portland or quick-setting cement, or bentonite clay. The minimum depth or length of casing that must be grouted is also determined by state regulations.

WELL COVER: A cap that screws or clamps onto the top of the well casing to prevent contaminants from entering the well.

SCREEN: A pipe-like attachment at the bottom of the well. Well screens are usually not required when drilling in bedrock, but they may be necessary if loose sand or fragmented rock is encountered. The screen is sealed on the bottom and has openings along its length that allow water to enter the well, but keeps out sand and sediment.

PUMP: Draws water from the bottom of the well and into the distribution system. Many types and sizes of pumps are available. The two most commonly used are submersible and jet pumps. Submersible pumps are installed in the well and can be removed relatively easily with the pull rope. Jet pumps have the motor located outside the well.

PITLESS ADAPTER: Provides a frostproof and sanitary hookup between the well and the household water distribution system. The pitless adapter must be located below the frost line.

Most residential wells withdraw groundwater that is replenished by rainfall entering the ground within a few miles of the well. For this reason, the way you, and your neighbors, and even those outside your community use the landscape can be an important factor in the quality of your water supply. Be alert to possible sources of well contamination such as septic systems, leaking underground fuel tanks, landfills, industrial spills or discharges, animal wastes, fertilizers, and pesticides.

Detecting groundwater contamination requires regular testing. You should test your water supply once a year for bacteria and nitrates. Consider seasonal testing if one sample shows elevated levels of these contaminants. Prolonged periods of heavy rain can flush contaminants into groundwater supplies.

At the least, test your water any time you notice unusual odors, colors, or cloudiness, or if you note an interrupted supply, such as pumping air or sediment. Contact your Health Department water quality division for information on which tests might be appropriate.

To get your water tested, you can call your Health Department to arrange for a water test (if they do them), or request a list of State-certified water testing laboratories serving your area.

Keep surface water runoff from puddling around the well. Grade your lot so that water drains away from your well casing. A well should not be drilled on a "low" part of your property.

Prevent surface water from seeping down the sides of your well. Make sure your well cap is not cracked and is tightly secured. If water tests show contamination, it is recommended that a well driller check the grout.

If your well is more than 30 years old, have it inspected by a county Health Department sanitarian or a qualified well driller to make sure that the casing is not cracked or corroded.

Install antibackflow devices on all faucets with hose connections, or maintain an air space between hose or faucet outlets and the water level in the container you are filling. Otherwise, you risk sucking contaminated water from laundry tubs, swimming pools, etc., back through the plumbing and into your well.

Have your fuel oil tank tested for leaks, especially if it is installed underground. Contact your fuel supplier for assistance.

Do not use gasoline, automotive products, solvents, pesticides, or excessive amounts of fertilizers near your well.

Do not tie pets to the well casing. Animal waste deposited close to the well could result in contamination. Also, a large dog may break or crack the casing.

Be careful never to hit the casing with a lawn mower or vehicle, or strike it with any force.

Maintain your septic system. Improperly functioning septic systems are a major cause of well contamination.

Your well should be disinfected with a chlorine solution any time work is done on the well or pump. Directions for shock chlorinating your well are available from your county Health Department. [Maryland Health Departments numbers and addresses.]


If there are unused or abandoned wells on your property, make sure they have been properly sealed to prevent direct contamination of groundwater by surface contaminants.

The above information and diagram is also available in a printed hard-copy file folder format. This file folder contains information that will help you maintain your private well system properly. The information is printed on all four panels of the folder, and the folder provides a convenient place for you to record and file receipts and information about your system. Keep it with other important documents about your home, and pass it on to future owners!

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