An old well you no longer use is not harmless just sitting there. Here is what abandoning or decommissioning a well actually involves, what it costs, and why it has to be done right.
State agencies, contractors, and well owners use the terms "abandon" and "decommission" to describe the same job: permanently and safely closing a well that is no longer in use. That is a specific, physical process, not a figure of speech. It means the well is filled and sealed from the bottom of the casing to the surface with an approved material, so it can never again be an open path between the ground surface and the water below it. A well that was simply capped and forgotten, or one that has a pump pulled and nothing else done to it, has not been abandoned in any legal or practical sense - it is just an unused well waiting to become a problem.
An old well is not neutral. Left unsealed, it works against you in two distinct ways.
A well casing is a shortcut straight down through the layers of soil that would normally filter out contaminants. Left open or poorly sealed, it lets surface runoff, fertilizer, bacteria, and spilled fuel or chemicals travel directly into the groundwater - and that groundwater does not stop at your property line. A bad well can foul your own water and your neighbors' wells drawing from the same aquifer.
Older, larger-diameter, or hand-dug wells can be wide enough to swallow a person. A loose cover, a rotted board, or ground that has settled around the casing turns an old well into a fall risk for kids, pets, and livestock - especially once it is buried or hidden by grass and brush.
Not every well on a property needs to be sealed today, but a few situations should push it to the top of the list:
In nearly every state, this work has to be performed by a licensed water well contractor. The steps look roughly like this:
A well cap is built to seal a well that is still in active service - it keeps insects and surface water out of the top of the casing while the well keeps producing. It was never engineered to hold back settling soil or to seal a well someone intends to walk away from permanently. Bolting a cap on an unused well and leaving it is not decommissioning.
Dropping rocks, debris, or dirt down an open casing is worse than doing nothing in some ways: it looks handled, but it is not. Loose fill leaves air pockets that settle and collapse years later, sometimes opening a sinkhole at the surface, and it does nothing to stop water from tracking down the space between the casing and the surrounding ground. That is why a surface cap or a filled hole is not an acceptable substitute for a proper seal, and why it is against the law in most states.
There is no single honest number here - the cost depends on depth, diameter, casing material, how much sealing material the job takes, and what your state requires. As a general sense of the range:
| Well type | Typical range | Why |
|---|---|---|
| Shallow, small-diameter well | A few hundred dollars | Less depth and material, simpler access |
| Deep or larger-diameter well | Roughly $1,000-$3,000+ | Significantly more grout or bentonite and contractor time |
| Large-diameter dug well, or one with stuck equipment | Several thousand dollars and up | Extra work to clear obstructions before it can be sealed |
Treat those figures as a starting point for a conversation, not a quote. Some states require specific sealing materials or extra documentation that adds cost, and a few offer cost-share programs that offset it. Get quotes from a couple of licensed contractors, and check your state's rules - including whether any assistance is available - in our state-by-state well guides before you budget for the job.
Most states require a permit before decommissioning work starts and a filed decommissioning or abandonment report once it is finished - similar to the well construction report filed when a well is first drilled. A licensed contractor typically handles this filing as part of the job. Requirements, forms, and fees are set state by state, so check what applies to your property before you schedule the work.
Check your state's well abandonment rulesAbandoning a well and decommissioning a well mean the same thing: permanently and safely closing a well that is no longer in use so it can never again act as a pathway between the surface and the groundwater below it. It is not the same as capping a well you still use, and it is not the same as walking away and forgetting about it. A properly abandoned well is filled and sealed solid, from the bottom of the casing to the surface, with an approved material such as neat cement grout, bentonite, or concrete.
In nearly every state, no. State well codes require this work to be done by a licensed water well contractor, and there is a good reason for that. Dumping dirt, gravel, or debris down an open casing leaves voids that settle and collapse over time, and it does nothing to stop surface water from tracking down the gap between the casing and the surrounding soil. A licensed contractor removes the pump and any obstructions, disinfects the well, and places sealing material from the bottom up so no gaps are left behind. Check your state's well-abandonment code before doing any of this yourself.
It varies quite a bit. A shallow, small-diameter well can sometimes be sealed for a few hundred dollars. A deep well, a large-diameter dug or bored well, or one with a stuck pump or casing problems can run into the thousands. Depth, diameter, casing material, how much grout or bentonite it takes to fill the hole, and your state's specific requirements all move the price. Get quotes from a couple of licensed contractors in your area rather than assuming a number - and check whether your state or county offers any cost-share assistance for decommissioning.
Most states require a permit before the work starts and a filed decommissioning or abandonment report once the well is sealed, similar to the paperwork filed when a well is first drilled. Rules, forms, and fees differ by state, so check the requirements for your state before you schedule the work.
Yes, in two separate ways. An unsealed well is a direct route for surface contamination - runoff, fertilizer, bacteria, fuel, anything sitting on the ground - straight down into the aquifer, and that can affect your water and your neighbors' wells too. It is also a physical hazard. A large-diameter dug or bored well with a loose or missing cover is a fall risk for kids, pets, and livestock. Both reasons are why an unused well should be decommissioned rather than left alone.
An unused well is not a problem that gets better on its own. Every year it sits unsealed is another year it can carry contamination into your water and your neighbors', and another year it sits there as a hazard. A licensed contractor can measure, seal, and document it correctly the first time.
Well abandonment and decommissioning rules are set state by state. The sources above illustrate typical requirements and process - always confirm the specific code for your state before starting work.
