Old and abandoned wells: why they need to be sealed

Many rural and older suburban properties have a well that's no longer used. It might be an old hand-dug well near the original farmhouse, a drilled well replaced when a new one was put in, or a well left behind when the home connected to city water. These forgotten wells are more than a curiosity. State health and environmental agencies treat them as a real risk to groundwater and to safety. This guide explains why, and what to do.

Why unused wells are a problem

The Minnesota Department of Health puts it plainly: every unused well that isn't properly sealed poses a safety, health and environmental threat to your family and community, and a potential legal risk to the homeowner.

Contamination. An unused well can act like a drain, giving surface runoff, contaminated water or improperly dumped waste a direct path into drinking water sources. That threatens your current well, your neighbors' wells and even city wells. Ohio EPA describes four ways an unsealed well can contaminate groundwater:

1. mixing water between aquifers;
2. letting surface water flow into the aquifer;
3. illegal disposal of contaminants down the well;
4. microbial contamination from animals that fall in and decompose.

Real cases. Wisconsin DNR describes a house that burned down over an improperly sealed basement well. The well let ash-laden water into the aquifer and contaminated a neighbor's well. In another case, a buried well covered only by a stone, near an animal yard and a septic field, severely contaminated water pumped from another well on the same property.

Physical hazard. Large-diameter dug wells in particular can be a fall hazard for children, pets and livestock if covers rot or shift.

Aquifer pressure. Ohio EPA notes that sealing also prevents further loss of pressure in confined aquifers.

Why old wells get forgotten

Wisconsin DNR explains that once wells are taken out of service, they're seldom used again. They're often forgotten after a property sale and may end up under a parking lot, an addition or a lawn. Once covered, a well can be very hard to find and evaluate. Where many improperly sealed wells exist, new wells may have to be drilled much deeper or into different aquifers to get safe water.

How to find an old well

Look for:

• pipes sticking out of the ground, anywhere from 1 to 8 inches wide according to the Minnesota Department of Health, sometimes cut off near ground level (sewer and septic pipes can look similar, so look closer if you're unsure);
• an area that stays wet, which can be a sign of an unsealed flowing well;
• a glass block or concrete patch in an exterior step, since older wells were often housed in a small basement room under the front steps;
• a concrete slab, pit or circle of stones near old farm buildings or the original house site;
• a depression in the yard that may mark a collapsed dug well;
• old pump houses, windmills or hand pumps;
• pipes coming through basement floors or walls;
• well records. Many states keep online databases of well logs.

Also ask the previous owners and neighbors, and check property disclosure documents.

Who can seal a well

This isn't a do-it-yourself job in most states:

• Minnesota law requires that a well be sealed only by a licensed well contractor. An unused well without a maintenance permit, or one that poses a health or safety threat, must be sealed. If a well was improperly sealed in the past, the homeowner is responsible for having it sealed properly.
• Wisconsin has required since June 1, 2008, that only licensed well drillers and pump installers fill and seal wells.
• Ohio EPA strongly recommends an experienced registered drilling contractor, and requires homeowners who want to seal their own wells to register with the Ohio Department of Health first.

Check your state's well program or local health department for the rules where you live.

What sealing involves

A contractor typically:

1. evaluates the well's depth, diameter, construction and any obstructions;
2. removes the pump, piping and debris where possible;
3. disinfects the well if needed;
4. fills it from the bottom up with approved sealing materials, often bentonite clay or cement grout, to restore a barrier to contamination;
5. cuts off the casing below grade and finishes the surface;
6. files a sealing record with the state.

Ohio EPA warns that a well sealed improperly is costly to fix, because the defective seal has to be drilled out. Getting it right the first time matters.

Timing and cost-saving tips

Wisconsin DNR notes that it's usually cheaper to seal an old well while the driller is on site building a new one. Some states also offer cost-share or financial assistance programs for sealing. Minnesota lists financial assistance for well sealing, for example. Ask your state program.

Selling a property with a well

Many states require disclosure. Minnesota, for example, requires a well disclosure statement before a purchase agreement is signed, listing the location and number of wells and whether each is in use. If you're buying, ask about old wells and include them in your inspection.

Protecting your current well in the meantime

Until an unused well is sealed, keep it securely capped, keep chemicals and waste away from it, and never use it for disposal. Minnesota recommends that homeowners test their water every year. CDC recommends annual testing for coliform bacteria, nitrate, total dissolved solids and pH. See well water testing.

Frequently asked questions

Can I just put a cap on it? A cap keeps kids and animals out, but it isn't the same as sealing. In Minnesota, for example, a well that isn't in use and doesn't have a Water Well Maintenance Permit has to be sealed, and if a well was capped or filled the wrong way in the past, the homeowner is responsible for having it sealed properly.

How much does sealing cost? There's no single price. The Minnesota Department of Health says depth, diameter, debris in the well, access and local geology all change the cost, so get several written estimates. It can cost less when a contractor is already on site, or when a group of neighbors hires one contractor to seal several wells at once.

Is there help paying for it? Sometimes. Minnesota notes that grants, cost-share programs and low-interest loans may be available, but they often require preapproval before the work starts. Ask before you sign a contract.

What paperwork should I get? In Minnesota the contractor must file a Well and Boring Sealing Record with the state and give you a copy. Keep it with your property records. It's the proof a buyer or inspector will want to see later.

Key takeaways

• Unused wells can carry contamination straight into groundwater.
• Look for old pipes, slabs, pits and depressions, and check state well records.
• Most states require a licensed contractor to seal a well.
• Seal old wells when a driller is already on site, and disclose wells when selling.