Old Wells and Abandoned Casings

Why this matters

An abandoned well is two hazards at once, and they belong to different people. The first is a hole: an old dug well under a rotted plank cover is a shaft a person or a child can fall into, and it may hold water and bad air at the bottom. The second is a pipe to the aquifer: any well left open, cracked or improperly filled is a direct path for surface water, fertilizer, fuel and sewage to reach the groundwater that neighbors still drink. A landscaper who finds the first and a plumber who finds the second are both standing at the start of a job that belongs to a licensed well contractor.

If you uncover a well opening, before anything else: stop the machine, move everyone back from the edge, and cover or barricade it so nobody can fall in. Nobody leans over it, climbs in or lowers themselves to look, whatever is at the bottom.

Three kinds of well, and what each looks like

• Dug wells are the old hand-dug kind: wide (commonly 2 to 4 feet or more across), usually shallow, lined with dry-laid stone, brick or clay tile, and topped with a wood cover, a concrete slab or a hand-pump platform. When abandoned, the cover rots, the lining shifts and the top of the shaft may sit just under the sod. These are the fall hazard.
• Driven wells are small pipe (around 1-1/4 to 2 inches) driven into shallow sand or gravel with a screened point. They show as a pipe stub in a yard or a basement, sometimes with an old pitcher pump on it.
• Drilled wells have a steel or plastic casing, commonly about 6 inches, running down to rock or deep aquifer. The casing sticks up out of the ground, out of a well pit, or through a basement floor in older houses that drilled inside. These are rarely a fall hazard and always a contamination path.

Cues around the property: a slab or platform with no purpose, a ring of stones, a low mound or a depression, a capped pipe out of a basement floor, a basement pressure tank with nothing connected, an old pump house, a buried electrical line running toward a spot in the yard, or a county record or seller disclosure that mentions a well.

Why an open or badly filled well matters below ground

A properly built well is sealed around its casing so water reaches the aquifer only by filtering through soil and rock. An abandoned one loses that seal in several ways: the cap is missing, the casing is corroded through, a cracked lining lets surface water run down the outside, or somebody filled it with trash, rubble or spoil. Spoil and rubble settle, leave voids, and pass water readily, so a well "filled in" with yard debris is often still an open conduit, just harder to see. That is why decommissioning (also called sealing, plugging or abandonment) is done by filling from the bottom up with a low-permeability material such as bentonite clay or cement grout, to the state's specification, by a licensed contractor who files a record of it.

Who regulates it

There is no federal rule for private wells. The Safe Drinking Water Act covers public water systems, and EPA's role for household wells is guidance. The rules are state well codes, and they range widely. Minnesota requires an unused well to be sealed by a licensed well contractor or kept under a maintenance permit, and requires a well disclosure statement when property is sold. Wisconsin requires unused wells to be filled and sealed to its well code with an abandonment report filed. Other states require sealing only when a well is found to be a hazard, or only issue guidance. Many states also require that when a house connects to a public water supply, the old well is either sealed or kept with a permit and physically disconnected from the house plumbing. Check your state's well program; this card is not legal advice, and what an owner must do at sale is a question for the owner's attorney or agent.

A temporary cover that actually covers

The fall hazard needs a cover the same day, before the crew leaves. For your employees on a construction job, OSHA's hole-cover rule (29 CFR 1926.502(i)) is a good standard to work to: the cover supports at least twice the weight of the workers, equipment and materials that could be on it, it is secured so it cannot be kicked or blown aside, and it is marked "HOLE" or "COVER". In practice that means a cover of sound material sized well past the opening on every side, screwed or weighted down, then barricaded and flagged so a mower or a child does not find it. The homeowner's family is not covered by OSHA, but the same cover protects them, and it is what you leave behind. A cover is a holding measure; the well contractor decides how the shaft is closed.

What each trade does on finding one

• Landscapers and excavators: stop, back the machine away from the edge rather than across it, cover and barricade, and keep the bucket from scraping around the opening, because the shaft lining at the top is often loose and can drop stones or collapse inward. Do not backfill it with spoil to make the problem go away.
• Plumbers: a casing or pipe through a basement floor may still be connected to the house water system or to a pressure tank. If a house is now on public water and the old well is still plumbed in, that is a cross-connection: well water can be drawn into the public supply. Separation is plumbing work with a permit in most places, and sealing the well itself is the well contractor's.
• Electricians and anyone else: a casing with a wire coming out of it may still feed a submersible pump from a live breaker. Do not cut or pull the wire. Treat it as energized until an electrician has traced it, locked out the circuit and proved it dead, per NFPA 70E Article 120 (120.5 in the 2021 edition, renumbered in 2024), with work practices at 29 CFR 1910.333(b)(2).

Worked example: two finds on one water-service job

A 1910 farmhouse is connecting to a new municipal water main. An excavator is trenching the new service line from the street, and a plumber is inside setting the meter.

Find one, in the yard. About 40 feet from the house, at 18 inches down, the bucket scrapes wood. The operator stops. The wood is rotted planks, and under them is a ring of fitted stone about 36 inches inside diameter. A flashlight from a standing position a step back shows water far down.

What he does, in order: shuts down and swings the bucket away from the opening rather than over it; keeps the laborer from kneeling at the edge to look; lays two sound sheets of 3/4-inch plywood across the opening, overlapping the stone ring by more than a foot on every side, screws them together and weights them; sets stakes and caution tape around a wide margin; and writes "HOLE" on the cover. Then he calls the job's general contractor and the owner.

The well contractor comes two days later, measures the shaft at 22 feet deep to the bottom, and seals it under the state well code. The volume tells you why nobody "just fills it in": a 36-inch shaft has a radius of 1.5 feet, so its area is about 3.14 times 1.5 times 1.5, or 7.07 square feet, and 7.07 times 22 feet of depth is about 155 cubic feet, roughly 5.8 cubic yards. That much trench spoil pushed in by the bucket would have settled, left voids and passed water straight to the aquifer; the contractor's sealing material is placed from the bottom up and recorded.

Find two, in the basement. In the corner of the basement, the plumber finds a 6-inch steel casing standing about 8 inches above the slab with a loose cap, a pitted pipe running from it to an old pressure tank that is still teed into the house supply, and a cable coming out of the cap.

What she does: she does not touch the cable, and asks the electrician on the job to trace it; it turns out to be live from a 240-volt breaker labeled "well" that nobody had switched off, which the electrician locks out and proves dead. She does not set the new meter with the old pressure tank still teed into the house piping, because that would connect the well to the municipal supply. She records it, recommends the owner have the well contractor seal this one too or keep it under permit as the state allows, and plans the separation as part of her permitted work.

Two finds, two different hazards. The yard well was a hole a person could fall into, closed by a cover the same hour. The basement casing was never a fall risk, but it was a live circuit, a cross-connection waiting for a meter, and an open path to the aquifer through a loose cap. A crew that treated both as "old well, cover it" would have handled the first correctly and left all three of the second's problems in place.

What changes the answer

• A record of proper sealing. If the owner has a sealing report for a well, the find is a buried record, not a hazard; note it and proceed, keeping the bucket clear of any marked location.
• An active well. A well still serving the house is not abandoned; the job is protecting it (no fuel, fertilizer or spoil near the casing, no damage to the cap or the line) rather than routing it for closure.
• A state that allows keeping an unused well. Some owners choose to keep an old well for irrigation where the state permits it. That still requires it to be disconnected from potable plumbing and protected at the top.

References

• See related: Recognize, Record, Route - the Rule for Legacy Materials; Private Wells and Septic for Non-Specialists; Cesspools and Pre-Septic Systems
• OSHA, covers for holes in construction, 29 CFR 1926.502(i)
• NFPA 70E Article 120 (120.5 in the 2021 edition, renumbered in 2024); OSHA, 29 CFR 1910.333(b)(2)
• Your state well program's code for well sealing and abandonment; EPA private well guidance