Window Well Leaks and Window Well Drainage
A window well is a bucket sunk against your foundation. It only works while it can empty faster than the sky fills it, and in Chicago clay that stops being true about the time the original gravel packs solid.
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The short answer
A window well leaks when it cannot drain. Water fills the well, rises above the bottom of the window frame and pushes straight through the seal. The fix is a drain at the bottom of the well, stone that still moves water, and a grade at the top that keeps roof and yard runoff out of the well entirely.
A window well holds back the earth so a basement window can sit below grade and still get daylight. Nothing about that shape drains on its own. Rain that lands in the well, snow that drifts into it and groundwater arriving through the backfill all collect in the same three or four square feet, and there are only two ways out: down through the soil beneath it, or in through the window. Close the down path and the window becomes the drain.
Chicago clay is what closes that path. A well dug into dense glacial soil drains slowly on the day it is built and slower every year after, as fines work down into the stone and fill the voids. Add a steel liner rusted at its fasteners, a downspout elbow aimed at the same corner and thirty winters of freeze and thaw, and one spring storm leaves eight inches of standing water against a window that was never built to hold any. Our basement waterproofing page shows where this sits alongside everything else we install.
Why does my window well fill with water?
A well fills because more water arrives than leaves. Every failure we find is on one side of that ledger or the other.
These are the five causes we actually pull out of the ground, roughly in the order we find them.
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The drain was never there
Plenty of wells in the older suburbs were set into a hole with a shovelful of gravel and nothing else. There is no pipe under them and never was. They drained acceptably while the disturbed soil was still loose, then quit once it settled and packed.
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The stone silted shut
Where a drain does exist, the failure is usually above it. Leaves, mulch, roof grit and clay wash settle into the stone until the voids are gone. From the top it still looks like a bed of gravel. Water now sits on it like a saucer.
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Roof water is aimed at the well
A downspout discharging within a few feet of a well delivers more water in one storm than rain landing in the well ever could. We find splash blocks pointing straight at wells constantly. It is also the cheapest item on this list to correct.
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The grade tips inward
Soil keeps settling against a foundation for decades after backfill, and the finished grade quietly rolls back toward the house. Once the ground at the rim falls inward, the well starts collecting runoff from that whole side of the yard.
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The well is too shallow for the window
A rim sitting flush with the lawn takes in surface water by design, and a well whose floor stops above the bottom of the window frame gives water a place to stand against the glass. Both are original construction rather than damage.
Signs it is the well and not the wall
- The stain runs downward from the window, not up from the floor
- It shows after rain or a fast thaw and never in a dry week
- There is a silt line or tide mark inside the well itself
- The sill and trim are rotting while the rest of the wall is dry
What ignoring it costs
- Rotted sills and frames, then a window replacement
- Steel liners rusted through, letting the soil behind them slump
- Water inside the wall cavity, which reads as a wall leak later
How does a window well drain actually get built?
A working well drain is a vertical pipe with somewhere real to go. The pipe is the easy half. The somewhere decides whether it lasts.
Here is the sequence on a typical retrofit, one well at a time.
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Dig the well out
Everything inside comes out: silt, old stone, leaves and whatever the last owner dropped down there. We take the floor below the bottom of the window opening so the finished stone ends up under the frame instead of level with it.
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Set a vertical riser
A perforated riser wrapped in filter fabric goes into the low corner of the well and runs down toward footing depth. The fabric is the whole reason this one will not silt shut the way the first bed of gravel did.
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Connect it to something that empties
The riser ties into a footing drain, an interior system or a line with real fall to daylight. A pipe that ends in clay is a hole, not a drain, and it is the mistake we correct more often than any other at a window.
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Refill with washed stone
Clean washed stone goes back, not pea gravel blended with the spoil that came out. Washed stone keeps its voids under load. Anything carrying fines becomes a plug again within a few seasons and you are back where you started.
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Rebuild the rim and cover it
Soil around the well is built up to fall away from the rim, the liner is re-anchored to the wall if it has pulled loose, and a clear cover goes on so the well keeps taking daylight and stops taking leaves.
What a finished well drain gets you
- The well empties between storms instead of holding a pond
- The window seal stops being the low point of the drainage
- Snowmelt has a route in February, when the ground is closed
- Drainage work backed by a 5-year warranty
Where these go wrong
- A riser that dead-ends in clay with nothing to feed
- Pea gravel or crushed fines standing in for washed stone
- A solid lid that traps moisture and rots the frame faster
- A cover fitted while the drain is still plugged, hiding the problem
Cover it, drain it, or both?
A cover keeps water out of the well. A drain lets water leave it. Those are two halves of one problem, and most of the wells we repair need both.
| Window well cover | Window well drain | |
|---|---|---|
| What it does | Keeps rain, snow and leaves from entering the well | Gives water already in the well a way down and out |
| Groundwater arriving through the backfill | No effect at all | Yes, that is the entire job |
| Drifted snow and fast melt | Mostly, if it seals against the rim | Yes, provided the outlet is not frozen shut |
| Typical install | An afternoon, often a homeowner job | Half a day per well, by machine or by hand |
| Cost | A stock lid is a hardware store purchase | Priced with the drainage scope after we see the well |
| Maintenance | Sweep it off and check the seal each spring | Almost none once the stone is clean and wrapped |
| What it will not solve | A well that has no outlet under it | A downspout still emptying two feet away |
| How it fails | Cracks, or the rim seal opens up | The outlet ends in clay, or freezes at daylight |
| Our warranty | Not a warranted repair on its own | Carries a 5-year warranty |
Neither one earns its keep while roof water is still landing beside the well. Extensions and grade come first: see grading and slope around a foundation.
Water standing in your window well? We measure the well, find the outlet or prove there is not one, and put it in writing free within 48 hours.
What we find by house era
Window wells were built differently in every decade of Chicago building, and the era usually predicts the failure before we are out of the van.
Pre-war bungalows and two-flats
Wells cut into the gangway long after the house went up, often just a curved steel liner pushed into clay with no pipe beneath it. With four feet of gangway, every drop off the roof lands within arm's reach of the well.
Usually no drain at all
Post-war block ranches
Galvanized liners set at backfill and rusted at the fasteners by now. The block wall behind them wicks whatever the well holds, so a wet well often shows up as a damp patch several feet from the window.
Drain it, then read the block
1980s and 90s poured walls
These frequently do have a riser tied into the footing drain, which means the pipe exists and is simply full. The tell is a well that keeps up in a light rain and floods in a hard one.
Clean it and reconnect
Newer subdivision homes
Deep wells with escape ladders, built correctly and then buried by settled grade and years of landscape mulch. The drain is usually intact under a foot of fines nobody has ever pulled out.
Dig it out, keep the wellWhat does window well drainage cost?
A well drain is priced as part of the drainage scope around the house, and the exterior corrections it normally rides with, downspout extensions and regrading, run $600 to $2,500.
| Work | Range | What moves the number |
|---|---|---|
| Downspout extensions and regradingtypical job | $600–$2,500 | Feet of grade to rebuild, soil hauling |
| Exterior French drainper linear foot | $45–$90 | Trench depth, where the water can legally go |
| Interior drain tileper linear foot | $95–$160 | Length of the run, slab thickness, what has to be moved off the walls |
| Sump pump with battery backupinstalled | $2,800–$4,500 | Pit condition, backup capacity, discharge routing |
A single well retrofit is small work, and we quote it in writing with whatever else the outside of the house needs, because fixing one well and leaving the grade alone is money spent twice. Full ranges for every line above sit on the pricing page.
When you do not need us for this
Wells are the one part of a wet basement a homeowner can genuinely fix in a weekend. We would rather say so than send a truck.
The downspout is the whole story
Move the discharge ten feet away from the well and watch the next three storms. Plenty of the wells we get called about never fill again after that. Downspout extensions cost a fraction of anything we would install.
Try this firstThe well only needs cleaning out
If a pipe is down there and it is merely buried in silt, pulling the stone, rinsing it and putting it back can restore the drain for the price of an afternoon. Wear gloves, and dig for a pipe before you buy any materials.
A free fixThe leak is the window, not the well
An old steel casement with a failed seal will leak in driving rain even when the well underneath is bone dry. That is a glazier or a window company rather than a waterproofing contractor, and the tell is water on the glass with dry stone below it.
Call a window shopA cover is all it needs
On a well that drains fine but catches leaves and drifted snow, a clear polycarbonate lid solves it for hardware store money. Buy one that seals against the rim rather than resting on top of it, and check it each spring.
A hardware store fixWindow well questions we get every spring
How do I know if my window well has a drain?
Dig down at the low corner of the well with a hand trowel. If a drain exists you will hit a vertical pipe, usually four inches across, within a foot of the bottom. No pipe after a foot of stone and clay means nothing was ever put under it. Do this on a dry day. On a wet one, the standing water has already told you the answer.
Can I just add more gravel to my window well?
Adding stone on top of silted stone raises the water level, not the drainage rate. The fines that plugged it are still down there and now they are deeper. If a well drains poorly, the stone has to come out and go back clean, ideally over a wrapped riser. Fresh gravel spread across a plugged well buys you one season and hides the problem for the next owner.
Why does my window well only flood in heavy rain?
Because a slow drain keeps up with a slow rain. A well emptying at a trickle handles half an inch spread over four hours and gets buried by the same half inch in twenty minutes. Storm intensity, not storm total, decides it. <a href="/basement-foundation-problems/leaks-only-in-heavy-rain/">Basements that only leak in heavy rain</a> almost always come down to a drainage rate somewhere in the system.
Do window well covers cause condensation or mold?
A solid lid with no ventilation can, particularly over a well that still holds water. Moisture evaporates, meets the cold underside of the cover and runs back down onto the sill. A vented or gapped clear cover over a well that actually drains does not have the problem, because there is nothing left standing in the well to evaporate in the first place.
Can a window well drain freeze in an Illinois winter?
The riser itself sits below frost in most installs and stays open. What freezes is the outlet, when the line runs to daylight and the last few feet sit shallow. That is why we prefer tying a well riser into a footing drain or an interior system wherever the layout allows, so the water leaves by a route that never meets February air.
Does a leaking window well mean I need a full waterproofing system?
Often not. A well is a point of entry, and when it is the only one, correcting the well and the grade around it is the entire job. What changes the answer is finding water at the cove joint or seepage on walls nowhere near a window, because that points at the footing rather than the opening. We put which one it is in writing before quoting anything.
Egress wells and walkout doors fail the same way
Anything cut into a below-grade wall becomes a low point in the drainage, and an egress well or an exterior stairwell holds far more water than an ordinary window well does. The mechanism is identical and so is the repair, but the volumes and the code questions are different enough to be worth reading separately.
Read about egress windows and walkouts
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