So, we live in a new house (moved in a year and a half ago as soon as the build was finished). We moved in during the dead of a Canadian winter. Even still, my sump pit would fill and pump put quite frequently. I knew the water table here was high, so not incredibly surprising. After about a month, we got a permit to route our sump to the sanitary floor drain which was great; didn’t have to worry about recycling water and creating a “fountain” effect.

Fast forward a year and a half and here’s the problem I’m facing. Although this past winter I noticed our pit didn’t fill nearly as much (chalk it up to water table changing and grading around the house actually being completed?), it has started filling like crazy over the past few days (mid-April) as the weather has suddenly warmed and we’re dealing with lots of snow melt. There’s no water resting directly against the house, but our whole area has a lot of pooling water. There are even little sloughs created across the alley past our backyard. So I feel like it’s inevitable that this rapid snow melt will affect the water table. Here’s the problem though—as my pit is filling, the water is coming in EXCLUSIVELY through a tiny gap between the bottom of the ABS pipe and the hole cut in wall of the sump basin that receives the inlet pipe. So the pipe itself seems to suddenly not be bringing water in; rather, water is coming in through a relief point through a crack between the inlet pipe and the basin wall (as it is not sealed all too well at all.)

I’ve called around and a lot of people seem to think it’s normal. They say that as the water underneath the slab gets higher/more saturated, the water is simply finding a relief point and is making its way through that crack. (Note that this isn’t a permeable/perforated pit; a solid pit with only the inlet and discharge pipes coming in/out.)

This makes some sense to me. However, I’m thrown off by how it seems like NO water is coming in through the inlet pipe anymore. Could it possibly have come detached under our slab? Most people I talk to seem to think not—they say the inlet pipe will be solid ABS pipe all the way to the outside of our foundation wall, after which point it will T off to perforated drain tile.

Anyway, let me know if this seems normal! I’m stressing over wondering if something underneath our slab is broken/detached and wondering if that’s why water is coming in through this crack instead of the pipe.


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    You don't want to seal a house's bottom too well. If you do, you know what you'll have? A boat. Then it becomes a numbers game: the weight of your house versus the weight of the water that wants to level the water table through your basement. We're dealing with fairly large numbers that are likely to break something. Apr 21, 2018 at 12:58
  • @Harper Right, I realize that, and that’s what I’m concerned about. That’s why I’m curious about if I should be adding another relief hole in the sump basin itself. It seems like with the large amount of water that’s obviously under my slab, there should be more than just this small crack to allow water into my pit. Let me know what you think.
    – Mike M
    Apr 21, 2018 at 17:41

1 Answer 1


Apart from routing a sump pump for water around a foundation to a sanitary drain (no storm sewers where you live?), this sounds normal.

Usually, the perforated piping is just a supplement to the classic French drain design using rocks. The pipe is to ensure there is always a path with low resistance when the water table gets high enough. Otherwise, some water should still find its way through the rocks/soil when the water table is above the sump pit basin and below the bottom of the pipe.

  • Thanks very much. Any thoughts, though, as to why the inlet pipe wouldn’t be bringing in any water at all? To clarify, are you saying that the water table happens to be in a “sweet spot” where it’s high enough to get to that relief point in the pit but not high enough to reach the drain tile? Again, just wondering why I haven’t seen this at all in the past 1.5 years, and now it’s been nothing but this for a week. Thanks.
    – Mike M
    Apr 21, 2018 at 4:55
  • @MikeM, yeah, that's exactly it. We have the same situation at our house. Water entering the perimeter drain enters higher up. There is gravel under your basement floor that can hold a lot of water as the water table rises. It has an easy path to drain into the sump pit, and that happens before the water table reaches the perimeter drain.
    – fixer1234
    Apr 21, 2018 at 5:33
  • @MikeM Where was the dump outputting water before? It sounds like it was probably just dumping it somewhere above ground nearby outside your home which just re-saturates the ground near your foundation and causes the pump to keep pumping it away (essentially what I believe you meant by your fountain effect comment). You also changed the grading around your foundation. WIth these updates, a significant reduction in water around your foundation is highly possible if the root cause was not an overall high water table. Apr 21, 2018 at 10:35
  • It only discharged water around the house for the first week—when it was dead of winter and -30 degrees Celsius (-22 F). It was creating a thick slab of ice, and so that’s why the city told us to re-route to the floor drain once we explained the issue. But yes, the grading around the house changed, and after that’s point I noticed it filling significantly less. Everything you’re saying makes sense, so I really hope you’re right. It is just somewhat shocking that I’m only now seeing water come through this crack rather than the pipe after 1.5 years—but snow melt just began, so maybe that’s why.
    – Mike M
    Apr 21, 2018 at 12:34
  • I just would love to see at least some water come through the pipe so I can have confidence something didn’t detach or otherwise fail. But maybe all this snow melt is causing the table to hit this “sweet spot” between the drain tile and the relief point in the pit—and that’s all there is to it. I sure hope so.
    – Mike M
    Apr 21, 2018 at 12:36

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