My window well has been filling with water - the base takes about 15 mins to fill before I have to empty with the manual pump - not very efficient especially at 3am. I’m in CO and we have had days of nonstop rain.

The top of the well slopes out and I have 2 tarps over the well. But the water still runs in at the base of the well where it meets the house. The top is dry. The drains are flowing. The basement sump pump is running. I’ve checked all the gutters and drainage pipes, but all seems to be clear. I don't know where else to look. I have looked for a drain pipe but can't find one. Seems these houses don't have one, so will continue to manually drain it.

What should I do? I have thought of using a good sealer to fill the gaps between the well and the home but won't know until it rains again.

Welcome to ideas on next steps.

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    What is the grading around the house like? Does the ground slope away from the house for 10-12 feet on all sides? I fully expect that water is coming up from the bottom. Percolates through the soil, is blocked/trapped by subsurface features, rises into the well. First thing is to make it drain away before it percolates in.
    – Ecnerwal
    May 12, 2023 at 12:16
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    As for 3AM pump outs - they make automatic float switch controlled pumps for that sort of thing.
    – Ecnerwal
    May 12, 2023 at 12:44
  • I think your answer lies here, "the water still runs in at the base of the well where it meets the house". Based on the pic, even if the tarp is keeping the rain out, it's soaking up through the ground and in through the no longer sealed gap between the house and window well retaining ring.
    – FreeMan
    May 12, 2023 at 14:45
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    @FreeMan I don't think it would even matter if the gap was sealed. Water will still come in under the "wall" of the well. I'm wondering how long this problem has been going on.
    – Huesmann
    May 12, 2023 at 16:24
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    @Clockwork, 'CO' is the US postal abbrevation for the state of Colorado. May 13, 2023 at 13:09

6 Answers 6


Sealing the well wall where it meets the house probably won't help much. I think the water in the ground is finding it's way under the window well barrier (by virtue of hydrostatic pressure) and moving up into the open area, to try and equalize the pressure of the water columns on both sides of the barrier.

The only way to really fix the problem (that is, prevent the well from filling with water) is to relieve the water pressure in the ground. This may involve some trenching, French drain (or similar) installation, to drain the ground water away from the house. This would need to be routed down slope (if possible) or maybe into a dry well.

I have a similar situation with an entrance to my crawl space. It fills with water even after the rain has stopped, sometimes for a day or two, depending on the amount of rain

So I did something similar to what you did, but I used a small ~$15 aquarium pump, dug out the well a bit (to create a sort of dry well), set the aquarium pump in the bottom ,and filled with some drainage rock.

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The aquarium pump is 115 VAC unit. I have it plugged into a smart plug that I can control from a cell phone app. This is nice when I'm away from the house but still want to run the pump for a minute or two.

Edit 1

Next on my radar screen is to marry the smart outlet with a smart water sensor that will turn the pump on and off automatically. Nice part about this is you don't need very much water for the sensor to work, as opposed to what you would need for a float type switch.

Edit 2 May 2024

One year later I have some observations to share, as to where the water is coming from. After rain has stopped, I can pump the well empty. A day later, there is water in the well that I again pump out. Two days after that, I repeat the process. Note that over the 3 or 4 days mentioned there has been no new rain. The water showing up in the well is migrating through the ground to the well.

  • Nice, but aquarium pumps are generally magnet-driven. It wouldn't take much debris to stop them right up.
    – isherwood
    May 12, 2023 at 14:27
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    I've had that setup for 3-4 years now. Pump still works fine. I also have it enclosed in a plastic coffee can (with holes), but that was more to protect the plastic pump from damage by the drainage rock. Finally, the pump seems to tolerate running dry (no water) fine.
    – SteveSh
    May 12, 2023 at 14:34
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    hydrostatic pressure. relieve the water pressure in the ground. +1 The Bizarre Paths of Groundwater Around Structures
    – Mazura
    May 12, 2023 at 18:33
  • Maybe something like a peristaltic pump that's designed to run dry safely and doesn't need to be primed. May 15, 2023 at 15:11
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    I don't disagree that there are ways my setup could be improved. What I put together was cheap ($20) and simple, and was intended just to be a "proof of concept". Just no reason to fool with something that's working.
    – SteveSh
    May 15, 2023 at 15:23

Push a tube into a pool of water. There's your answer. It's not complicated. Even with proper grade slope the ground can become saturated down at that level.

My parents have a similar problem and ended up installing outlets and battery-backup sump pumps at each well on the high side of their home. This was about 20 years after construction when drain tile loops in their clay soil had silted in and clogged. Storms were resulting in water coming up to and through the windows.

So you can either excavate and install a robust drain system or do what you're doing now in one form or another. You aren't going to succeed in waterproofing a window well. That's not a good plan.

  • Shortly after we moved into our present house, there was a tropical storm that dumped a lot of rain. The sump pump in the crawl space was running every 60 secs. I poked my head inside the crawl space and heard running water, that was coming in through one of the craw space vents. The landscaping and dirt had built up so much around that vent that groundwater had no where to go, So there I was in middle of this downpour with a pick ax digging the dirt and roots away from the vent and giving the water someplace to go, other than into the crawl space.
    – SteveSh
    May 12, 2023 at 18:42
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    That's about how it usually goes. My folks' story is about the same. We then had to pull up carpet the next day to get it dried out. Fortunately the water that comes in tends to be clean and not muddy.
    – isherwood
    May 12, 2023 at 18:45

The drains are flowing. The basement sump pump is running. I’ve checked all the gutters and drainage pipes, but all seems to be clear. I don't know where else to look.

You skipped a step here: WHERE is that water flowing to? A lot of times, people think gutters are to keep water from just rolling off the roof, but gutters and sump pumps are part of an ecosystem to channel water away from your house. If it runs down the downspouts and ponds on the ground next to your house, it's literally making the problem worse. The water needs to run somewhere away from your house. That might mean installing drain pipes to move the water away.

Your window well is also full. Silt has clearly filled the gravel at the bottom so water has nowhere to go. Digging it out and removing the silt should make it drain better.

  • 1
    Yep and in old homes with literal clay tile systems, the downspouts often go into a porous pipe that is nestled up against the foundation. The idea was that it would work kind of like a french drain and take any water near the foundation away from the house but the reality is the opposite, especially once ground shifts and breaks up the pipe. When I had mine redone, I was informed the old-style system was strictly illegal in my locality and that the drain tile needed to be solid pipe from the downspouts.
    – JimmyJames
    May 12, 2023 at 20:39
  • Also, the silt build up you note could be a sign that the drainage for the well (there should be some, I think) could be clogged.
    – JimmyJames
    May 12, 2023 at 20:47

My strong suspicion is that that well is supposed to be draining effectively into the sump pit.

In my house I have 4 window wells with hardware (corrugated metal and window frame) that is identical to your. Two of the wells have catchments that drain into the foundation drain lines that lead to the sump pit. They have a grated cover that is just a touch below level with the top of the coarse gravel in the well. The other two have no exposed catchment and they are intended to drain either directly through the gravel or through a buried riser pipe into the foundation drain line below.

I am not sure why some are drained and others not, I suspect it has to do with the slope of the foundation drain line below, or maybe with the way the architect/engineer believed the water might come of different parts of the roof. I have never had them flood, even when they were completely surrounded by standing water, the drainage to the sump is direct.

At any rate, your window wells would have been designed to drain water under worst-case conditions which leaves two possibilities:

1-The designer did not accurately estimate what the worst-case water ingress was. Perhaps once in a century flooding or failure to account for ground water saturation from closely situated neighbor whose downspout is close to your window.

2-Something is not as the designer intended. Maybe something is occluding a part of your foundation drain lines. Maybe excessive settling has messed up the slope of the lines so that your well is now at a low spot. Bottom line is that the well is not really intended to keep water out in the first place, but rather to be able to drain it freely.

It sounds like you have already looked at your downspouts and sump pump. How full is the pit getting? Does it run almost continously? Can you see where the foundation lines drain into the pit and how much water is flowing from the line that would drain that well? Is the water ejected from the sump so that it cannot flow back to the foundation?

My understanding is that if your drain system is working, water should never really be sitting at that level against your foundation, so that even if sealing the well to the house helped, it might just be treating the symptom and not the bigger issue.

I would dig,carefully, in the bottom of that well to try to find a drain. If the material you are digging through is largely dirt and fines, I would replace it with the appropriate grade of gravel for draining. If you find a riser, try to flush it out maybe a leaf blower+duct tape or possibly a snake. In a <30yo house I would expect to be able to find information on the existing sump system somewhere.

IDK if its possible or appropriate to dig all the way to the foundation drain line, which I believe is usually at or below the top of the basement floor, but if you did I would think you could splice in a tee and riser up to a catchment for the well.

Last, if a drain could not be found, I would consider setting up a compact sump and pit down in the bottom of that well.


The correct but difficult way would be to run new french drains beneath the level of the well, run them into the street or a dry well or a pumped sump pit if necessary.

An easier way, since you already have a sump pump inside, would be to put a small drain at the bottom of the window well and drain it into the inside French drain. You should feel uneasy about introducing a path for water to travel from outside to inside; this puts more stress on the sump pump and adds to the cost if the pump fails. However, in this case, the amount of water appears to be small. Just a few inches at the bottom of the well. If the amount of water became greater, it would leak in via the window anyway wouldn't it? Think about this. You don't want to introduce a path for large amounts of new water into your basement. But if it's assured to be small this is a relatively easy fix, just let it drain into the existing system.


All the other answers have great points. Deeply investigate WHERE the water is coming from. If it's from the roof or surface, that has to be dealt with. That said, if it's ground water or just saturated ground, it has to have a route downward once it collects at the bottom of the well. In Seattle, we have mostly glacial till, a clay-like substance under our shallow soil. This drains horribly and very slowly.

An old timer shared a brilliant idea he's used for years. In the event that you simply can't get a drain and move the water away from the window, dig a pit the size of a 5 gal home depot bucket on the outside of the well. Add 4" of depth. Then take a 5 gal bucket and drill ~30 1/4" holes in it. Place the bucket in the hole upside down and bury it in rock. This will collect the water. At that size, it should be enough for most applications to buy time and get that water moving deeper into the ground instead of up towards your windows and foundation wall.

Hope this is helpful for anyone who reads this!

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