I had to replace a 4 foot section of cast iron pipe under the slab, so I jack hammered the floor and filled it back up with concrete. During the rainy season, the water table can get high and water enters the basement around the patch. (The vertical ABS pipe is not the culprit)

Basement floor concrete patch with water intrusion

I applied hydraulic cement around the edges but it didn't quite work out as you can see, maybe user error, maybe the wrong material. I prepped the joints as directed, AFAIK.

Would any of these approaches work?

  • A concrete crack sealant (there are a lot to choose from)
  • Remove and reapply the hydraulic cement
  • Break up and redo the concrete differently
  • Some kind of floor coating like epoxy or paint
  • Anything else? Due to how this basement was constructed in the 50s after the house was already 40 years old, there are some changes that would undermine the foundation, so I think a sump pump would be problematic

There isn't a lot of water pressure, just a slow leak.

Note that I'm not looking for a particular product, just a general approach to solving this problem.

  • Water can seep though most joints. Most sealing done from on top/inside is usually temporary at best. Will be better to drain water away/add a sump pump to remove the water.
    – crip659
    Commented Jan 8 at 22:32
  • The time to think about waterproofing your patch area was BEFORE you added the concrete.
    – Ecnerwal
    Commented Jan 8 at 23:00
  • @Ecnerwal could it be worth the time to remove the patch and redo it? I think it was 2 bags of quickrete so nbd. How would you go about waterproofing in that case?
    – Ed Norris
    Commented Jan 9 at 0:30
  • @Ecnerwal, I'm not sure what that means. What sort of waterproofing can be installed under a patch?
    – isherwood
    Commented Jan 9 at 13:49

2 Answers 2


You shouldn't be thinking in terms of crack seal (caulk, etc.). That's a whack-a-mole fix. You should be thinking in terms of a coating, which is a more comprehensive fix.

Drylok is one brand of such a product, but there are undoubtedly others. Looks like there's something similar on your walls now.

  • Shouldn't the real objective here be to minimize the elevation of the water table?
    – Huesmann
    Commented Jan 9 at 13:40
  • 1
    Sure, but that's not what was asked. I'm not going to propose installing a drain tile system and sump when I was asked how to seal a seam. Coatings exist for a reason.
    – isherwood
    Commented Jan 9 at 13:48
  • I've done what I can before completely regrading the yard - new French drain and two new catch basins at low spots that tie into a system that takes the water to the street. But in the PNW rainy season, there's a lot of water
    – Ed Norris
    Commented Jan 9 at 16:15

I would recommend Aquron. It is water based, silicon liquid that needs to be applied at high pressure so that it penetrates the pores. It then seals the concrete. I have had good outcomes with it in a lift shaft that used to fill up.

However, due to warranty issues, in NZ at least, they will not sell you the product any more, you have to use one of their recommended applicator guys.

Note, I am not associated with them.

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