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I have a home with an elevator pit that sits below grade in an area with a high water table. Whenever I get a heavy rain or high tide the elevator pit fills with about 30 gallons of water. I did notice a crack in the concrete between the side wall and the pit floor.

Question: What is the best way to seal the concrete and the crack to prevent continued water seepage?

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  • should be same answers as any basement ...
    – keshlam
    Feb 12, 2015 at 21:30

2 Answers 2

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...which is to say, you need a sump pump, because you will NEVER reliably stop it from the inside, and there's not likely to be any way you can gain access to the outside of the pit to waterproof it properly - and "properly" does indeed mean "from the outside." If you cannot waterproof from the outside, all you can do is pump it away, in any basement (other than hillside ones where sometimes you can just pipe it away, but that evidently would let the tide in more effectively for your situation.)

You can TRY painting things on the walls and caulking cracks or filling them with hydraulic cement, but hydrostatic pressure usually wins and the leak returns.

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  • How well does a sump pump work where the water table is so high and so porous and free flowing that even a high tide can cause water incursion? Can a sump pump keep up with the water?
    – Johnny
    Feb 13, 2015 at 1:35
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    Most likley, yes. Sump pumps are available in different sizes/pumping capacities - would be most accurate to pump out the water during high tide and measure how fast it returned in order to choose a pump size, but as a rule, it's not difficult to get a pump that will exceed the inflow rate; you can certainly also try to reduce the inflow rate by filling the crack. Do be sure to direct the pump outflow a reasonable distance away from the building
    – Ecnerwal
    Feb 13, 2015 at 2:05
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I would humbly disagree with the other persons answer in this way... You CAN stop the leak from the inside using a concrete sealant called Creto DPS (sealer)and Creteo RMO (filler). Unfortunately the RMO product is only sold to contractors but the DPS can be purchased online. I would drain the pit, wait until low tide, and seal the area with the sealant. DPS works with the water so residual water in the concrete won't affect the curing process. Use a silicone caulking like Dap that cures in under three hours to fill any visible cracks. Then put a space heater in the pit, maybe on a milk crate, to help the curing process. Problem solved!

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