My basement is leaking in an area where I just had a sewer line installed. I had dug a square into the basement floor concrete, so that the plumber could run the new sewer line under the floor. The job went great but almost immediately the hole in the concrete began to fill with water. This pit is near a wall.

This seems strange because we never had water leak into the basement in this area. We have, however, had leaks in this basement in other areas, when it rains really hard.

Eventually some months ago it stopped filling with water in this pit, so I had the pit covered back with concrete. Lately water is leaking in this area again, and it's coming in through the wall near this pit, and also water is seeping up through the edges of where the pit was filled with concrete.

I imagine I could use drylok paint, hydraulic cement, radon seal, etc. But that won't make the water underneath the floor go away.

What I want to try is digging a new hole near where this pit is, and near the part of the wall where water is coming in. Then I'll insert a sump pump liner, and when it fills up I have a swimming pool pump and hose that I can use to drain the water out the window and down a long way into the yard, away from the house.

So my question is, to kinda reiterate, would it be a good idea to dig a hole for a sump pump liner near the area where this sewer line was covered up? Or is there a better way to attend to this new water leak?

BTW eventually if this does work, I'll put in an actual sump pump and have it pump into a nearby DWV pipe (with a trap of course).

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    Find out if your sewage is combined storm and sanitary. If not, your sump should drain to outside surface so it flows towards a storm sewer. You can do this with your temporary hose solution by running it through a window. Don't pump storm water into a dedicated sanitary sewer.
    – jay613
    Feb 25, 2021 at 11:45
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    are you 100% certain that this is water seeping up through the concrete and not a leaky joint in the plumbing?
    – FreeMan
    Feb 25, 2021 at 14:21
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    I'm guessing the guy who installed the new line didn't completely back-fill around the pipe. Now you have a void under the floor for water to collect in and then leak up thru the existing hole in the concrete. It may be impossible to open up enough access to fill the void. Feb 25, 2021 at 15:42
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    @Mark you should talk to neighbors and local pros about this. If neighbors have sump pumps you can probably do it safely. If subsidence is a problem in your area you should probably look to restore the waterproof floor rather than remove water from the soil. Also sump pumps need maintenance and they also need power during storms when you are most likely to not have power. Restoring the waterproof floor is an option you should look at seriously if you never had water issues before this project.
    – jay613
    Feb 25, 2021 at 18:33
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    @Mark if you change "Can" to "Should" and clarify in the question whether you ever had any problems anywhere in your basement with groundwater before you broke the floor, I will provide an answer. But FYI the components of the answer are already in my comments!
    – jay613
    Feb 25, 2021 at 22:14

1 Answer 1


You should not immediately dig in this spot but you should do some research, get some expert advice and probably should put in a sump system to keep your basement dry.

If you have water entering your basement during rain storms it’s a good idea to implement a drainage system. There are different approaches but you’re suggesting a sump pit and pump. I have that in my basement, it’s quite effective. It’s not necessarily the right solution to put a sump pit in the location you describe, just because you see water there. Since you have water appearing elsewhere also, you should do some planning to put the sump pit in the best location.

If subsidence is a problem in your area you should not do anything that will remove a lot of water from the soil. Neighbors and local pros will be able to give you information about that. If neighbors have sump pumps that’s a good sign.

If water elsewhere in your basement is coming through the walls you might consider a french drain and sump pit combination. Read more about those elsewhere, but briefly it’s a trench dug around the inside perimeter of your basement and filled with perforated tubes and gravel to collect water and direct it to the sump pit. OTOH if water is coming through the floor you might need more than one sump pit. You’d best get an expert to look at it before you start digging in this one spot.

The location of the sump pit should be where its drain will have easy access to exit the house and then, with as short a run of pipe as possible, drain water onto the ground where it will run away from the house. You have to think about the outside grade, where the drain will go, and where the water will flow from there. During a storm you could be pumping hundreds of gallons per hour and you don’t want it all collecting around your house or your neighbor’s.

I don’t think your pool pump experiment will prove very much. If you don’t have much rain, but you do have a little water in that one spot, and you pump it out …. would that spell “success”? It really isn’t proving anything, only that the amount of water in that one specific spot given the amount of rain you’ve had during your experiment is (or is not) within the capacity of your pool pump. It’s not an interesting experiment.

If you have a combined sanitary and storm sewer service, you might be allowed to pump sump water into it but even then it’s not a good idea. If your main drain line (from your house to the street) becomes clogged during a storm, your sump pump would then cause black water to rise up all through the house. If you have separate sanitary and storm sewers you must not pump storm water into the sanitary sewer. Best thing is to drain the pump outside where water flows away from your house.

You should run a new dedicated electric line from your panel for the sump pump. If you have a nearby 20A outlet that isn’t used for very much else you could use that but don’t plug it in to the outlet shared with your washing machine, dehumidifier, or any other large appliance and especially not your basement fridge or freezer.

You should bear in mind that sump pumps need power, and power fails usually during storms, when sump pumps are most needed. If you rely on the pump to protect a (future) finished basement you should consider backup solutions, either generator power or a backup sump pump. A backup pump uses no electricity, it uses water pressure from your city water supply to drive the pump during power outages.

Hopefully that helps, but in summary: you should not dig a sump pit in this one spot just because you recently damaged the floor there if you also have water entering your basement elsewhere. Instead you should plan to dig drains and a pit that will serve your whole basement. You should not run your pool pump experiment because it doesn’t prove anything useful.

  • @isherwood thanks. How can you see if I did that or not? You do not appear to be a moderator and my deleted answer appears to be visible only to me (and maybe moderators). So how do you know I didn't do what you suggest? I didn't, just wondering how this works.
    – jay613
    Feb 26, 2021 at 16:40
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    I'm not a moderator. After so many rep points you see dead answers. They're "pinked out". Not a big deal. Just a suggestion.
    – isherwood
    Feb 26, 2021 at 16:42

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