The sink drains have become blocked in a duplex apartment. There is a bathroom on either side of a shared wall, with each sink belonging to a different living space in the duplex. There is a straight pipe between the sink drains: if I remove both traps I can see through it. The setup is something like this:


That tee in the middle is inaccessible - it is between two walls and above the subfloor. Running a snake from a sink obviously doesn't work, and it would take a lot of liquid plumber to fill up both traps and the bottom of the horizontal pipe.

Under the house, there isn't any access that I can see. I'm not a plumber, though, so maybe I'm missing something. Here's a mediocre picture of the pipes (the purple circle in both images represents the same elbow):


Any suggestions would be appreciated!

2 Answers 2


The most obvious choice is to modify the plumbing at the point indicated below to allow for a cleanout plug to be added.

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The fitting shown would be replaced with one that looks like this:

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In such installation the straight through part of the Wye Tee fitting is closed off with a plug which is easily removed to insert a cleanout snake.

Adjusting the plumbing in this type installation is not the simplest job and rework with plastic (PVC or ABS) is often done. There are compression clamp fittings that can allow plastic pipes to be mated inline with cut off iron pipes. The availability of the Wye Tee in plastic is much better for larger diameter pipes such as these drain pipes.

Some folks would simply cut out the iron pipe at the indicated area do the necessary snaking to clear the blockage and then install replacement plastic fittings with the compression clamp fittings without allowing for a cleanout plug. The concept being that the compression fittings are easily removed in the future if access is required.


Get two bladder-style drain cleaners.

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Insert one down each sink. Turn them both on simultaneously and they'll inflate until they block up the sinks, at which point they'll fill the plumbing in between the two and use pressure to push the blockage down the only remaining path.

If this drain proves to be problematic in the long-term, then you'll have to modify the plumbing. But there's no reason not to try the simplest solution first!

  • If the OP elects to use this approach they should evaluate the type of fittings and piping used under the sinks through the P-Traps. Most of the more modern trap setups use some types of joints that are not designed for high pressure. In particular where a slip joint fitting is sealed with a compression ring washer around the outside of the slide in part if the fitting high pressure could make fittings blow apart.
    – Michael Karas
    Commented Apr 13, 2015 at 1:43
  • That's excellent information! From the photo in this case OP seems safe, but future visitors should definitely look twice. Hopefully the more modern plumbing would also use a Y instead of a T to let the snake function properly.
    – mhlester
    Commented Apr 13, 2015 at 2:18

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