How to Cap or Decommission an Old Well
An old well that no longer supplies water shouldn't just get a lid. Proper decommissioning, also called sealing or plugging, means a licensed well contractor pulls out the old pump, pipe and debris, then fills the whole well from the bottom up with grout and files a sealing record, as Minnesota's well handbook describes.
In many states you aren't allowed to do it yourself. Minnesota law, for example, says only a licensed well contractor may seal a well, and EPA's advice is to hire a certified well driller for any well abandonment and closure.
Why a cap alone isn't enough
A capped but unsealed well is still an open pipe into the groundwater. Minnesota's health department warns that an unused well can act as a drain, giving surface runoff and contaminated water a direct path into the aquifer that you and your neighbors drink from. It can also leave you liable if that contamination reaches someone else's well.
The old water itself is another reason. Water sitting in an unused well for years picks up whatever drains in, so don't hook an old well back up to the house without a contractor's inspection, disinfection and a lab test.
Find the old well first
Many old wells are hidden. Minnesota's guide to lost wells lists the usual signs:
- A steel pipe sticking out of the ground, often 1 1/4 to 6 inches across
- A concrete slab, a low circular dip in the yard, or a damp spot
- A small room off the basement, often under the steps, or a patch in the basement floor
- An old windmill, which usually stands right over the well
- Old pressure tanks, pumps or wiring coming through a basement wall
Ask previous owners and neighbors, and check state well records and county permit files. If the house was there before city water reached the street, assume there's at least one well somewhere on the lot.
Tools and parts
This is mostly a hiring job, so your list is short:
- A heavy temporary cover and stakes or fencing to secure the well until it's sealed
- Your property survey and any well records you can find
- A phone list of licensed well contractors (your state health department keeps one)
The contractor brings the rig, the grout and the tremie pipe.
How a well gets decommissioned
Confirm the rules
Call your county or state health department. Many states require a licensed contractor, a notice or permit, and a sealing record. Don't assume your town's rule matches anyone else's.
Get estimates
Minnesota's health department suggests getting several, and notes the price can drop if a contractor is already on site drilling a new well or if several wells are sealed at once.
Ask about cost-share
Some state and local programs offer grants or low-interest loans, and preapproval is often required before you sign.
Clear the well
The contractor removes the pump, drop pipe and any debris. Sometimes the casing has to be perforated so grout can seal outside it too.
Grout from the bottom up
The well is filled completely with grout pumped through a tremie pipe from the bottom up. Pouring material in from the top leaves voids.
File the record
The contractor sends a sealing record to the state and gives you a copy. Keep it with the deed. Minnesota sellers must disclose wells to buyers, and that record is your proof the job was done right.
Mistakes to avoid
- Filling it with dirt, rocks or trash. It settles, leaves voids, and still lets surface water down. EPA says never to dispose of waste in an abandoned well.
- Cutting the casing off below ground and burying it. EPA says not to cut the casing below the land surface. A buried, unsealed well is still a pipe to the aquifer, and now nobody can find it.
- Bolting a lid on and calling it done. A cap keeps kids out. It doesn't protect the groundwater.
- Hiring someone unlicensed. In states with licensing, an improper job may leave you paying for it twice. Minnesota makes the owner responsible for getting an improperly sealed well redone.
Keep it instead?
If the old well is in decent shape, a contractor can sometimes inspect, disinfect and return it to service for irrigation or as a backup. In Minnesota, a well you keep but don't use needs a Water Well Maintenance Permit with an annual fee. Our well inspection guide covers what a contractor checks, and well casing problems covers the repairs old wells usually need.
When it's a pro job (nearly always)
Sealing a drilled well takes a rig, grout pumps and in most states a license. A homeowner's part is finding the well, keeping it safe until the contractor arrives, and keeping the paperwork. There's no reliable national price, because cost depends on access, depth, diameter, debris and the geology.
FAQ
How do you cap a well?
For a well you're still using, a sanitary cap bolts onto the casing with a gasket and screened vent. See our page on well caps. For a well you'll never use again, a cap is only a stopgap until it's properly sealed with grout. In Minnesota, only a licensed well contractor may seal a well.
How do you cap an old well?
Cover it temporarily with something heavy that can't be lifted by a child, then have a licensed contractor seal it. The contractor clears out the old pump and debris and fills it with grout from the bottom up.
How do you cap a well pipe?
A threaded or slip cap will close a small old well pipe for now, but it's still an open path to the groundwater underneath. Mark it, then get it sealed. Small-diameter pipes are often old driven wells, and they need the same treatment.
What do I do with an old well pump and tank?
If the well is being sealed, the contractor pulls the pump and drop pipe as part of the job. The old pressure tank in the basement can be disconnected and removed once the well is out of service.
Sources
- Minnesota Department of HealthWell Owner's Handbook: A Consumer's Guide to Water Wells in Minnesota (opens in a new tab)
- Minnesota Department of HealthSealing Unused Wells (opens in a new tab)
- U.S. EPAProtect Your Home's Water (opens in a new tab)
- Minnesota Department of HealthFinding Lost Wells: Searching for Wells on a Property (opens in a new tab)