# sump pit depth



## andreacarlene (Aug 14, 2011)

how deep should a sump pit be? Does the water level nee dto be kept below the holuse footings?


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## Bud Cline (Mar 12, 2006)

*What is the source* of the water you intend to evacuate?


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## Just Bill (Dec 21, 2008)

Most premade pit tubs are about 2', but I have used shallower containers on occasion. How deep it needs to be depend on how your drainage system is designed. A deeper pit just means the pump won't run as often.


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## oh'mike (Sep 18, 2009)

The float on the pump should be set to the height of the water table---if it is below the level of the floor.

You do not need to drain the pit below the footings----no benefit and might just wear out the pump trying---

Tell us what's going om---What are you concerned about?


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## andreacarlene (Aug 14, 2011)

We purchased a home which had "blooming" underneath vinyl on half the basement slab on possession. Ugly surprise! We think the water vapor got trapped under the vinyl and led to the problem but can't be certain. The other half of the basement was tested with a moisture meter and is dry - it has carpet. We think the vapor was able to evaporate through the carpet so no issues. The water table in our area is higher than usual this year and all of the moldy areas were at edges of walls - most exterior.

A foundation expert advised a 36" deep sump pit and pump. He was vey rushed and had no time to provide information or answer questions. We also decided to install a backwater valve on the sanitary line at the same time and discussed the sump with the plumbing company. They indicated they would install a 36" deep pit with a 3/4h pump and exterior discharge. In the end I have a 24" deep pit with a 1/4h pump and discharge to the storm sewer. Not what we paid for and I unfortunately did not get the specifics in writing. They have agreed to come back, install a 1/2h pump and an exterior discharge so we have the option of manually switching the discharge either way with a shut off valve. My concern is that this would leave our footings standing in water as the pit is 24" deep and the combinined pump, float and lab height are 14". That leaves the water approx. 10" under the slab. The footings would be 16" under the slab - so in 6" of water. I am worried that my water issues may be due to moisture wicking up the footings and walls and that if I don't re-do the pit to 36" - which would leave the water approx. 6" under the footings - that I may solve nothing. 

Of course we will try to negotiate with the plumbing company but they have developed selective amnesian and I may need to do this at our own cost to fix it properly.

Thanks for any advice!


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## oh'mike (Sep 18, 2009)

No harm will come from having the footings below the water table.

Water under your floor covering could be from a lack of Poly vapor barrier under slab--could be other causes,too.

All you will get out of a super deep pit is a super big electric bill.

Call a couple of basement water proofers and get more expert advice--

and please don't offer your self diagnosis --let them talk--you listen--

I believe you are off base with your efforts to drain your footings---see what they suggest.


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## Daniel Holzman (Mar 10, 2009)

Agree with Mike, there is no gain in draining concrete footings. Your objective is to keep water from your basement floor. Significant quantities of water DO NOT wick up footers, that is an urban legend. Mike is correct in that failure to place a water barrier such as polyethylene underneath the slab can lead to soil moisture saturating the slab, which can lead to a variety of issues such as damp floors, mold on the floor, even mushrooms occasionally. This problem is solved by proper placement of a moisture barrier, not by lowering the water table an extra foot, although if you have unlimited funds you can do that too.


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## andreacarlene (Aug 14, 2011)

OK ... not sure if there is a poly barrier or not. This is a basement so I don't think placing one now is an option? There is a lot of gravel under the slab -maybe 1 1/2 feet. Is assume this provides a good capillary break? We also have weeping tile but not sure how it is placed - it does drain to the storm sewer with a backflow preventer. Any ideas why a foundation expert would recommend a 36" deep pit?

Thanks!


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## oh'mike (Sep 18, 2009)

That's not a standard practice----he must have something in mind--what that is and is it a proper solution is what I was questioning.

Seek another opinion from a basement water proofer.


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