Water Well Casing Construction
Leak Symptoms,
Air Vents,
Troubleshooting Diagnosis, Repairs

Definition of well casing: what's a "Well Casing" anyway?

A well casing is a steel or plastic pipe that is used to seal and support the sides of a drilled water well. The diameter of a residential water well casing is usually 2" to 6" but much larger steel casings are used in some water wells.

A photo of the above-ground portion of the well casing is shown in the photo at the top of this page. In that photo we can tell that this well uses a submersible (in-well) pump because we note the well wiring electrical conduit at the side of the well casing, bringing electrical power to a pump that's in the well.

In our sketch shown here, (adapted from ACE Forensic Engineering in Atlanta and used with permission) the well casing is shown in cross section, represented by the two vertical red lines in our drawing at left. But of course actually the well casing is a round steel pipe.

This drawing left crams more parts into a small space than you'd find in a real water well - we've got the submersible pump up there near the top of the well casing; actually the pump will be located a few feet or more off of the well bottom, and actually in most water wells the steel casing extends from the ground surface down into bedrock but the well bore itself continues down through that rock to a deeper depth - the casing does not extend to the very bottom of the well.

While soil and well designs vary as ground, soil, rock and water availability also vary in different areas, generally, after the well has been drilled the casing is driven into the drilled opening in the earth to a dept that (usually) inserts the bottom of the casing in bedrock.

The drilled well depth continues downwards into bedrock, through which water flows into the well.

A grout is then pumped around the steel casing to seal the casing bottom and sides against water leakage into the well.

How does water get from the well, up the casing, and into the building?

When the well construction is nearly complete, a hole is cut in the side of the well casing near ground level (below the frost line in freezing climates). The water piping that picks up water from the well near its bottom is routed up the center of the well casing until it reaches that exit opening in the casing side.

There the piping (and the water it carries) exits the well casing through a pitless adapter (a fitting that seals the hole in the casing), continuing on to bring water to the building the well is serving.

See WATER PUMPS, TANKS, DIAGNOSTICS for further explanation of well pumps and water storage tanks or pressure tanks and their controls.

See WELL CAPS & COVERS - well casing cap sealing and venting requirements

How to Repair a Leaky Well Casing: choose between drilling a new well or installing one or more well casing repair sleeves

Leaks in steel water well casings can be caused by a variety of troubles including corrosion, pressure from stones or other objects outside the casing, splits at a welded or defective casing seam, even a lightning strike, and nearby construction that includes blasting.

The shallow well at our New York laboratory produced clear potable water from 1920 to the 1990s when the town of Poughkeepsie decided to re-route the highway near our property. Nearby rock blasting was followed by the sudden and persistent appearance of silt in our drinking water.

The photo (left) of a roughly 2" x 3" hole in a well casing is provided courtesy of Link-Pipe, a no-dig well casing and water main repair / well-rehabilitation company[2].

Link-Pipe's literature calls this well casing hole corrosion damage but we think the edges of the hole and that protruding rock sure make it look as if the casing side was broken through by pressure of the stones and earth or other pressures outside the well.

It can be difficult to know that your well casing pipe has developed a leak. But common symptoms that lead to an investigation of the condition of the casing (possibly requiring a CCTV camera) include

• Sudden appearance of dirt, sand, debris in the water supply
• A reduction in well flow rate
• A new bacterial or other contamination problem in the well water.
  
  Leaks into a well casing risk carrying surface or groundwater contaminants into the water delivered by the well.

Leaks in the well casing are a problem because of the risk of leaks of  surface contaminants into the well.

Our second image (left) shows the side of the same well casing after Link-Pipe's well casing sleeve has been installed.

Well casing repair sleeves are suitable for repairing damage to a well casing that permits leaks into or out of the well casing.

Using a Repair Sleeve to Fix a Leak in Steel Well Casings for Water Wells

Presuming that the surface water or groundwater leak into a well is not occurring right at the pitless adapter that carries well piping out through the side of the casing (that's high enough to be repaired by digging down to it outside the well casing itself), there are indeed repair sleeves designed to fit inside of a wide range of well casing diameters.

Repair sleeves for well casings may use different repair approaches (resin-sealed to the old casing or dry "Filter-Sleeve" a patented alternative used by Link-Pipe, a no-dig well casing and water main repair / well-rehabilitation company[2] ( Tel: 800-265-5696 ).

The casing repair sleeve is inserted with monitoring by a CCTV to be sure that it's properly located. [Images & tech review requested 6/27/12, Image at above-left courtesy Link-Pipe]

Repair sleeves are designed to fix a specific leak spot in a well casing - often one that occurs near the top of the water level where oxygen and water combine to increase the risk of corrosion.

The installer lowers a well casing repair sleeve, a cylinder small enough to slide into the casing, to the point where the casing is leaking, and then using one of several methods, seals the sleeve to the surrounding well casing to block the casing leak or damage.

Typical well casing repair sleeve lengths run from six inches to three feet.

The sleeve assembly is lowered into the well to the depth of the leak problem and then affixed in place. Depending on the sleeve type the internal diameter of the well will be reduced by about an inch or inch and a quarter.

This should still leave sufficient space to be able to pull and restore the well pump, foot valve, etc. If not, you're in trouble.

The photo at left (courtesy Link-Pipe) shows the filter sleeve assembly along with a CCTV monitoring camera being lowered into a well.

Low pressure pipe repair sleeves are used in both wells and water mains, result in a reduction in well casing diameter of about 1 1/4 inches, and use a resin-soaked gasket around the sleeve exterior surface to seal the contact space between the repair sleeve and the original well casing.[2]

For petroleum wells and possibly water wells, " Pressure activated sealants have been used on numerous occasions to repair casing leaks with the tubing in place.  A major advantage in utilizing this technology is that the sealant will only solidify where the leak is active.  In addition, the material is easily removed by mechanical means and will not add difficulty to future work over operations if required." [1]

For injection wells the petroleum/gas industry has developed ultra fine cements that are used in a slurry form as well as other injectable sealants like Injectrol to seal well casings, but with varying success. [3]

High pressure dry-type well casing repair sleeves use air or water to expand the sleeve to seal the well casing once it's in place. The sleeve has to be securely locked in place before the installation is ended, lest it slip down and expose the leak it's trying to seal.

This approach depends on fine suspended solids in the water supply to eventually clog and thus seal the sleeve against the original well casing and can easily seal a 2" to 3" hole in the well casing. [2]

A well casing repair sleeve does not line the entire well casing - it'd be way too costly.

Investigate These Questions Before Using a Well Casing Repair Sleeve

Before launching a well casing repair sleeve project, an assessment of the condition of the entire well casing is in order as well as a determination of why the leak has occurred - the leak source.

For example, if a casing is leaking because it's splitting along a welded seam,  or if large sections of the casing are badly corroded, we may be pessimistic about the future of other casing sections and a repair sleeve approach may make no sense.

I have read that it can be difficult to accurately locate some casing leaks, and in the petroleum industry very sophisticated (and expensive) methods are required that are just not going to be practical nor affordable for a residential water well.

If a well casing has multiple leaks, is splitting, or is badly corroded I'd question the economics and feasibility of the repair sleeve approach.

Unfortunately it's probably new-well time for most homeowners at that point - we don't find many residential water well drillers pulling the entire casing to replace it, though that may be done in the petroleum industry.

Also I would listen to the advice of an experienced local well driller in deciding how to repair the well. And if no one in the area has experience installing a well repair sleeve, that option may be out of the question anyway.

Finally, in deciding on the repair versus replace question for a residential water well, one would consider the performance of the current well as well as its age and casing condition. If the well is marginal or modest, that may argue against a costly repair.

On the other hand, as corrosion in a well casing may be local to the usual top of the static head in the well, the repair sleeve approach may make sense.

Drilled Well Annular-Space Leaks Around the Well Casing

Leaks Around the Well Casing Rather than Through It

A different well water leak, failure to seal the annular space around the well casing exterior, risks contamination of conventional drilled wells as surface and ground water leak down into the aquifer around the casing.

Illustration adapted from: Michigan DEP Flowing Well Handbook [PDF] (Michigan DEP Website)

And an annular space leak around an artesian well sends water to the surface, eroding soils, flooding lands, wasting water, and causing other trouble. Discussing leaks around the outside of the casing of an artesian well, the Michigan DEP points out,

Sealing the annular space surrounding the well casing is critical, since an ineffective seal or absence of a seal can result in the uncontrolled discharge of water on the outside of the well casing pipe.

When ground water breaks out on the outside of the well casing, erosion of the confining geologic layer and other overlying materials can occur. The uncontrolled discharge of ground water from flowing wells can cause flooding of the well site and adjacent properties and damage to nearby structures. [8]

Michigan and other states regulate the construction of artesian wells to require that the well is constructed so as to

• prevent unnecessary discharge of water from the aquifer to the ground or ground surface
• protect the aquifer against contamination
• protect against erosion and confine the water flow to within the well casing

Details about artesian wells and leaks around the well casing rather than through it are provided

at ARTESIAN WELLS, Well Spools

How can I fix a leaky residential water well casing?

Our water pump in the well recently went out and we hired a crew to replace the pump. However I am concerned if he used correct procedure and if caused more problems than we started with.

When he first started pulling up the drop pipe the "spool" was stuck and he had problems with pulling it up at first, once it came free he set it back down and took the cable off.

Then he came up to the house and told me he is going to pour some acid down to soak over night and loosen up the "spool" so he could pull it up, he dumped about 2 gallons of it down there and the next day he pulled everything up again.

Later when he started blasting out the black water a bunch of sand came out and he told us we need an entirely new well because there is a hole in the case, and sleeving the case wasn't an option.

However after he left I was looking at the pipes and wire left that was pulled up and they have some bad corrosion just above the water level. I am wondering if the acid he poured down the casing ate through the casing where it sat overnight and caused the hole? Also there was no sand to be found in the old pump which makes me more suspicious.

Is this acid treatment normal and safe for the casing? Is he telling me the truth that no one ever "sleeves" the case and that its not an option?

Thank you ahead of time for any information about this, I am not made of money and can't afford to be taken advantage of. Thanks again - B.T. 4/25/12

Reply: function of well spools & using well casing repair sleeves to repair well casing leaks at residential water wells

Details about finding and fixing well casing leaks are

at WELL CASING LEAK REPAIRS.

Excerpts are just below.

A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem, and I'm not at all sure I have a full picture of what's going on with your well.

That said, here are some things to consider about well spools, leaks in the well casing, and using acid to free up a stuck well spool in your well.:

OPINION: when you are not comfortable with advice you've received ("you need a new well") start by asking your well driller to explain his reasoning. Most contractors are quite honest and are not out to gouge you, but they were not English majors and may not be expert in communication.

A well spool is a special seal around the well piping used to seal a well casing in wells at which the static head of water level in the well casing rises above the frost level. Basically it's a "spool-shaped" plumbing fitting that incorporates round flanges at its top and bottom, threaded to accept well pipe fittings above and below the spool.

Well spools are required on artesian wells or "flowing wells" in freezing climates.[8] Without this component the upper well casing could be split by freezing water.

The illustration of a well spool at left, edited from a schematic provided by Baker Manufacturing who apparently obtained it from ACE Engineering illustrates the part of this assembly.

The well spool is held in position by a hold-down spider to keep the spool from being pushed up in the casing by the pressure of water rising in the well casing, and O-rings seal the well spool to the well casing itself. - Ed. [Permission & tech review requested 6/27/12]

Details about artesian wells and well spools are at ARTESIAN WELLS, Well Spools

Fixing a leaky well casing - re-drill versus well casing repair sleeves

Leaks in the well casing are a problem because of the risk of leaks of  surface contaminants into the well.

Repair sleeves for well casings may use different repair approaches (resin-sealed to the old casing or dry "Filter-Sleeve" a patented alternative used by Link-Pipe, a no-dig well casing and water main repair / well-rehabilitation company ( Tel: 800-265-5696 ).

The casing repair sleeve is inserted with monitoring by a CCTV to be sure that it's properly located. [Images & tech review requested 6/27/12]

Repair sleeves are designed to fix a specific leak spot in a well casing - often one that occurs near the top of the water level where oxygen and water combine to increase the risk of corrosion.

The installer lowers a well casing repair sleeve, a cylinder small enough to slide into the casing, to the point where the casing is leaking, and then using one of several methods, seals the sleeve to the surrounding well casing to block the casing leak or damage.

Typical well casing repair sleeve lengths run from six inches to three feet. The sleeve assembly is lowered into the well to the depth of the leak problem and then affixed in place.

Depending on the sleeve type the internal diameter of the well will be reduced by about an inch or inch and a quarter

. This should still leave sufficient space to be able to pull and restore the well pump, foot valve, etc. If not, you're in trouble.

Finally, in deciding on the repair versus replace question for a residential water well, one would consider the performance of the current well as well as its age and casing condition. If the well is marginal or modest, that may argue against a costly repair.

On the other hand, as corrosion in a well casing may be local to the usual top of the static head in the well, the repair sleeve approach may make sense. Like  you I'm nervous about pouring acid or any potentially toxic chemical into a well.