new french drain installation, empty cisterns + wet floor

You mean the sump pump pits?

Just wait for some rain. They will fill up.

It had been raining all day when the concrete floor photographed was covered in water. That water is streaming from the top of the knee walls, which are the footer under the old foundation.

My thought is that the only way the French drain was done correctly is if the only source of water into the basement is over the top of these knee walls. Else I have a problem like the French drain not being sloped.

That water is streaming from the top of the knee walls, which are the footer under the old foundation.

My thought is that the only way the French drain was done correctly is if the only source of water into the basement is over the top of these knee walls.

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Ayuh,...... It appears that there's no path for the water behind the knee-walls, to the drains, so it comes out at the top,.....
It just ain't gettin' to the french drain,.....

What's the grades, Outside the house,.....
That's usually where the Cure is for water problems,....

percentjuice said:

That is not the fault of the waterproofing company.

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Don't be too quick to dismiss that, hopefully they did it right and you just didn't include pictures of the drainage and waterproofing.

There's a corrugated pipe sticking into the sump pit, but is that just a new interior loop, or connecting an existing footing tile drain from outside, or connects to both old and new? Yes, it appears water either sitting on the old footing ledge outside or crossing under the old footing is coming in and some cold joints too. If you have water under the slab, make sure there are holes in the sump crock sides to let that in.

Bondo said:

Ayuh,...... It appears that there's no path for the water behind the knee-walls, to the drains, so it comes out at the top,.....
It just ain't gettin' to the french drain,.....

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Not coincidentally, the waterproofing company is offering to saw cut the perimeter and install waffle-plastic drainage to allow just that. All at an additional charge.

Also correct is that the outside drainage is a future todo, but it doesn't relate to the quality of the French drain. Am hoping the community can help determine if the existing job was mismanaged.

Math Notes: The basement is 50 feet long. The top of the French drain inlet pipes are two inches below the surface of the concrete floor. The concrete floor is at least 2" deep and above a gravel bed.

Did you see the french drain go in.

That pipe also comes in non perforated, that would be a mistake you don't want to pay for. The corrugated plastic to catch water around the edge should have been put in with out discussion.

Nealtw said:

Did you see the french drain go in.
.

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Effectively not. They had gravel over it before I was able to view.

percentjuice said:

Effectively not. They had gravel over it before I was able to view.

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On the pipe sticking into the pit, can you see perforations?

Water will take the path of least resistance. If it comes down the outside of the wall, and there's a crack above the slab, it'll take that path, rather than continuing to flow down underneath the slab, where it'd get into your french drain.

Quick question per my Math notes above: The French drain clearly has zero fall in a very large basement. Should this be a "redo the drain" situation, or is this a normal oversight of sorts?

percentjuice said:

Quick question per my Math notes above: The French drain clearly has zero fall in a very large basement. Should this be a "redo the drain" situation, or is this a normal oversight of sorts?

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That is fairly normal. That shouldn't cause a problem.

It doesn't matter that your french drain has zero slope; it's there to provide the water that filters into it a clear path to your sump pit (which should have a lower bottom elevation than your french drain). It's also not intended to provide high flow capacity—if you have high flow in it, you have bigger problems!