Window Well Leaking Into Basement? How to Stop a Flooded Window Well

Water coming in at a basement window is a common problem once the fall rain starts. Someone finds the carpet soaked under the rec-room window, or a puddle on the floor of a basement suite, and assumes the foundation has failed.

Often it hasn’t. A window well leaking into basement space is usually a problem with the well itself: a clogged drain, a well full of leaves, or water being sent into it. Sometimes it’s the window. And sometimes it really is the concrete. This post walks you through how to tell which, what you can fix yourself this weekend, and when the wall around the window needs a proper repair.

How a window well floods

A window well is a small open box set against your foundation so a basement window can sit below ground level. Most have a drain at the bottom, often hidden under a layer of gravel, that carries rainwater away.

When that drain works, rain falls into the well and disappears. When it doesn’t, the well fills up like a bucket. The water pools against the bottom of the window and the concrete wall around it, and it stays there as long as the rain keeps coming.

Here’s what usually causes window well flooding:

• Leaves and needles. In late October and November, leaves fall straight into open wells and mat down over the drain. It happens right as the heavy Lower Mainland rain arrives, which is why window wells so often overflow at this time of year.
• Soil and gravel washed over the drain. Over time, dirt from the garden and fine gravel settle into the well and slowly seal the drain.
• Downspouts discharging nearby. A downspout that empties beside or toward a well can fill it fast.
• Ground sloping toward the well. If the soil around the well slopes in, the well collects runoff from the yard as well as the rain that falls in it.
• No drain at all. Some wells were built without one, or the drain line is blocked further down where you can’t see it.

Window well leaking into basement? Check the well, the window and the wall

Before you fix anything, work out where the water is actually coming in. There are three common culprits, and they need different fixes.

Water over the sill or around the frame

If the well fills above the bottom of the window, water can spill over the sill or push in around the frame. You’ll often see it running down the inside of the window or pooling on the sill before it reaches the floor.

Water can also come in around the frame even when the well isn’t full, if the seals or caulking around the window have failed. That’s a window issue, not a concrete one, and a window specialist is the right call for it.

Water running down the wall below the window

If water shows up on the wall below the window, especially in a line running down from one of the bottom corners, it’s often coming through a crack in the concrete.

Concrete is weakest at the corners of openings like windows. Stress concentrates there as the house settles and the concrete shrinks, so cracks tend to start at the corners and run down or out at an angle. When the soil around the well is soaked, water can come through that crack even if the well itself isn’t overflowing.

A simple hose test

If you can’t tell which it is, try this on a dry day:

1. Dry everything inside: the sill, the wall below and the floor. Clear stored items away so you can see.
2. Run a garden hose into the empty well for 10 to 15 minutes. Aim it at the bottom of the well, not at the window.
3. Have someone watch inside with a flashlight. Note where water first appears and how long it takes.
4. Next, try the window frame on its own. Let things dry, then run the hose gently over the window frame and glass, not into the well.
5. Compare. Water during the well test points to the drain or the wall. Water only during the frame test points to the window.

Keep it simple and safe: don’t stand in a deep well, and don’t flood a well that already isn’t draining. If water appears below the window during the well test, look closely at the corners for a crack.

Window well drain clogged? How to clear and test it

If your window well drain is clogged, here’s the DIY routine. Wear gloves; wells collect all sorts of debris.

• Scoop out leaves and soil. Get everything out down to the gravel. A small hand shovel or a gloved hand works fine.
• Find the drain. It’s usually under the gravel near the middle or one side of the well. You may need to move some gravel aside to find the grate or opening.
• Clear the grate. Pull off any matted leaves, roots or silt, and rinse the grate if you can.
• Rinse or replace dirty gravel. If the gravel is packed with soil, clean or replace the top layer so water can get through to the drain.
• Do the bucket test. Pour a bucket of water into the well and watch. It should drain away steadily, not sit there.
• If it doesn’t drain, the line may be blocked further down, or there may be no drain at all.

Make this part of your fall basement leak prevention checklist, and check the well again once the trees are bare.

Clearing or replacing a blocked drain line is a separate job from clearing the top of the well. If your well still won’t drain after you’ve cleaned it out, ask us whether it’s part of your problem when we come to look at the wall.

Window well covers: do they help?

Window well covers sit over the top of the well and keep most leaves, rain and debris out. For a lot of homes they make a real difference, especially under trees.

Pros:

• keep leaves and debris off the drain
• keep most rain out of the well
• make wells safer for kids and pets

Cons:

• can trap moisture, so condensation may build up under the cover
• some block light into the basement (clear covers help)
• leaves pile up on top and still need clearing

One important point: if the basement window is an emergency exit, especially for a bedroom or a suite, the cover must open easily from the inside. Check this before you buy.

Also keep the gravel and soil in the well a few centimetres below the bottom of the window. If the fill sits right up against the window, even a little water in the well reaches the frame.

When the concrete around the window needs repair

If the well is clear and draining, the window frame passed the hose test, and water still comes in below the window, the concrete is the leak. The same goes if the hose test points straight to a crack running down from a corner.

A cracked wall under a window is a concrete problem, and covering it with caulk from inside rarely holds once water is pushing from behind. We seal those cracks from the inside (negative-side repair). We open up the crack, stop any running water with Krystol Plug and treat it with Kryton crystalline materials such as Krystol T1, which react with moisture to seal the concrete itself. Where the crack needs it, we use compatible injection. To learn which cracks need attention, see which leaking cracks need repair.

Working from inside may avoid costly excavation or window-well work in some cases. It depends on what’s going on at your window, which is why we quote from a site look, not a phone guess. If someone recommends rebuilding the well, digging outside or installing a new drain, ask us whether it suits your house. Our foundation and basement leak repair and crack repair pages explain our approach.

If water is coming in at other spots too, see why foundation walls leak after heavy rain or how to find the source of a basement leak.

What to do while it’s raining

If a basement window leaks when it rains and it’s happening right now:

• Soak it up. Use towels or a wet vac to keep water from spreading into carpet and drywall.
• Move things away from the wall. Get furniture, boxes and electronics out of the way.
• Photograph where water enters. A short video showing water coming over the sill or down from a corner crack is extremely helpful.
• Bail the well if it’s safe. If the well is full and you can reach it safely from the surface, bailing it out with a bucket lowers the water against the window. Don’t climb into a deep, flooded well.
• Call us while it’s active. We’d rather see a leak while the water is running, because it shows exactly where it’s getting in.

Common questions

Why does my window well fill up with water?

Usually because the drain at the bottom is clogged with leaves, soil or silt, so rain has nowhere to go. Other causes include a downspout emptying nearby, ground sloping toward the well, or a well with no working drain at all. Clear the well, find the drain, and do a bucket test to see whether water drains away.

Should every window well have a drain?

Most window wells are built with some way for water to drain away, often a drain under the gravel at the bottom. If yours fills up and doesn’t empty after you’ve cleared it, find out why. The drain line may be blocked further down, or there may not be one. Ask us whether it’s part of your leak when we look at the wall.

Do window well covers stop basement leaks?

They help. A cover keeps leaves and most rain out of the well, so the drain stays clear and less water pools against the window. But a cover won’t fix a cracked wall below the window or a failed window seal. If water comes in even with a covered, dry well, the leak is coming from somewhere else.

Why does water come in below the window even when the well is empty?

It’s likely a crack running from the corner of the window. Concrete is weakest at the corners of openings, so stress cracks often start there. When the soil around the well is soaked after days of rain, water comes through that crack whether or not the well is full. Our guide to which leaking cracks need repair explains more.

Can a crack under a basement window be fixed from inside?

Usually, yes. We seal cracks from the inside by opening up the crack, stopping any running water and treating it with crystalline materials, with compatible injection where the crack needs it. Whether it’s the right fix for your window depends on what we find, so we start with a site look before we recommend anything.

Is it a window leak or a window well leak?

Do a hose test on a dry day. First run a hose into the bottom of the empty well for 10 to 15 minutes and watch inside. Then let it dry and run the hose over the window frame only. Water during the well test points to the drain or the wall; water only during the frame test points to the window seals.

Book a free inspection

If you’ve cleared the well and water still comes in at your basement window, give us a call, ideally while it’s raining. We repair leaking basement walls from the inside for homeowners across Vancouver, Burnaby, Richmond, Surrey and the Fraser Valley. Read more about our foundation and basement leak repair, then call (778) 686-2221 (Mon–Sat, 8:30 AM–5:00 PM) or book a free inspection.