I recently purchased a home that has a shower with no drain trap. The home is built on a concrete slab. I plan to gut and replace the shower (and break concrete/re-work plumbing) eventually. However, I am curious if there is some sort of mechanical trap that could be used in the short-term?

I am thinking something that could just be temporarily placed inside the 2" drain pipe (like this for repairing toilet flanges). I am just trying to prevent the nasty smell/gasses that are coming up it (although it is just tied into a grey water line, not sewer). We are hoping to continue using the shower even in the short-term before we can get it fixed correctly with a P-Trap.

  • Are you sure it has no trap? Someone screwed up royally if that's the case. Could it be just dried out? – isherwood Apr 8 '19 at 20:24
  • I suppose it is possible, but I have put a lot of water down it. Even after putting water down it, if I turn the bathroom vent fan on there is breeze coming out of the drain. I have not sent a camera down it (I don't have one), but looking with a flashlight I can a good distance down and there is no water pooling. – Bill Apr 8 '19 at 20:27
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    Did you do a product search? My five seconds yielded this contraption, for example. – isherwood Apr 8 '19 at 20:28
  • Here's another. – isherwood Apr 8 '19 at 20:29

Sounds like what you want is a screw-down test plug:

Test Plug

Test Plug

These come in the major drain pipe sizes. The rubber provides a good, temporary seal even if the surface is a bit irregular. I'm used to seeing them with a metal top and bottom plate, but I guess they have moved on to plastic.

  • Thanks! However, we were hoping that the shower could still be used. It looks like this will also prevent water from going down. I was hoping I could find something with a mechanical flapper of some sort to allow water down, but prevent smells from coming up. – Bill Apr 8 '19 at 20:15
  • Well, it has a simple thumb screw so it can be removed and replaced by anyone. I'm not aware of a temporary one-way valve that would be flush with the shower floor, allow water down, and keep air from getting out. – JPhi1618 Apr 8 '19 at 20:17
  • This doesn't close the overflow passage, either. – isherwood Apr 8 '19 at 20:23
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    @isherwood, I was assuming this was a floor drain for a shower only, not a tub/shower combo so no overflow. Guess I could have asked for clarification. – JPhi1618 Apr 8 '19 at 20:25
  • Benefit of the doubt granted. :) – isherwood Apr 8 '19 at 20:27

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