I have an iron pipe underneath my slab. I busted it this morning when I was working on an adjacent pipe. It is a seam-split, parallel to the pipe's axis (i.e. the split runs long-ways on the pipe).

I feel like there's something I should be able to do to fix the dilemma, given that the pipe is right there, i.e. I already have a giant hole in the wall, the slab is already dug up adjacent to the pipe, I can reach underneath AND I have a direct vertical access to the hole, only about 6 inches from the split.

I've heard about these sort of "stents" similar to an artery stent, made to patch pipes from the inside - I've also considered cutting the pipe off underneath the slab and attaching a new fitting (though I would feel like the pipe, at this point, wouldn't be durable enough to accept a new fitting if it's in the habit of splitting at the seams).

I've also given some consideration to fiberglass repair kits, like those sold by Fernco

I really would like some input from others. What are my options to fix the dilemma?

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  • Replacing the pipe is the only way to go. I have trenched in new pipe and run overhead for hot and cold. It’s a lot of work.
    – Ed Beal
    Dec 27, 2020 at 18:11
  • The pipe needs to be wrapped to protect it from concrete alkyds (alkylides?).
    – ojait
    Dec 27, 2020 at 18:51
  • The problem with making a repair under a slab is you shouldn't use a union which would ease the repair.
    – ojait
    Dec 27, 2020 at 18:53
  • @EdBeal we are moving out of state in april, so we don't want to do a bunch of costly repairs - is replacing the pipe really the only fix?
    – Tyler M
    Dec 27, 2020 at 19:40
  • 2
    With galvanized once it starts splitting it is almost impossible to rethread. They usually break at a coupling or T as this point is thinner and the galvanized is stripped off when threaded. You may have better luck than I have. Having the threading equipment and trying to repair ended up costing more. If you can work back to a coupling a threaded adapter can convert to plastic pipe cpvc or pex I have had limited success with this method as the stress on the galvanized causes T’s or couplings to split. If you are able to repair, remove the aerator and high flow to flush rust & scale out.
    – Ed Beal
    Dec 27, 2020 at 20:33

2 Answers 2


TLDR: I ran brand new pipes down from the attic, and disconnected corroded old ones.

Update on what I ended up doing (the idea may help someone else):

I tried using plumber's epoxy on the pipe but it didn't hold. Then I tried a fiberglass resin, and that didn't hold.

Then, I called a plumber who basically said I'm SOL, but he offered to replumb my house for a little more than I'm willing to pay. But I liked his idea, so I disconnected all the connection points for that run of pipe, then dropped new PEX tubing down from the attic and tapped in at all those points. So now I have an unused pipe sitting in the ground, which isn't a problem for me, and I have hot water again.

  • I know what SOL is, I seam to live in a constant state of it. What is TLDR?
    – Alaska Man
    Dec 29, 2020 at 20:36
  • Usually means: "too long, didn't read"...
    – handyman
    Dec 29, 2020 at 20:40

Damage like that cannot ever be repaired properly. It can be bodged however. The question you have to ask in these situations is "would I be happy to find this in a house I'd just bought?". Hopefully the answer is no.

As others have commented, this pipe should be replaced either in its entirety, or at least back to a coupler on sound pipe, that is the only proper and correct way to repair such damage.

  • 1
    I see that now. The part of the puzzle I was missing was "how" to replace it. I really didn't want to tear up the floors because we had just put them down recently, and the pipe would extend into another room so it would be lots of demo work. But the clarity I got of "leave the pipe and run a new one from a more easily accessible location" really sparked the bulb for me
    – Tyler M
    Dec 29, 2020 at 20:13
  • Using a new run is a great idea (well done) and one which usually only comes when actually looking at the job. Not always obvious for us remote 'armchair' plumbers. The new home owners will thank you :-)
    – handyman
    Dec 29, 2020 at 20:42

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