After a shower the toilet floods and slowly drains during this process the tub gurgles. Could this be the Tom's waxed doughnut or the vent up through the attic/roof? Thank you for your time and expertise!

  • 2
    I'm calling it "Tom's waxed donut" from now on, that's great.
    – JPhi1618
    Sep 20, 2019 at 14:17
  • 6
    Sounds like a bit of a plugged drain down stream from the shower. But I got a chuckle out of “tom’s wax donut” also.
    – Ed Beal
    Sep 20, 2019 at 14:23
  • 1
    Yes, you probably have a blockage. Please update your question to describe the layout of your plumbing. There's not enough information here to troubleshoot through the internet.
    – isherwood
    Sep 20, 2019 at 15:19
  • Does the shower drain back up too?.... still laughing at the donut..
    – JACK
    Sep 20, 2019 at 15:20

2 Answers 2


Gurgling from the tub drain and/or slow draining showing could be from either a partial blockage in the drain line OR a venting issue. However, this should not raise the height of water in the toilet bowl assuming it's at the same floor level. The water level in the tub/shower would have to back up to an equal level for that to happen. Unless of course you're flushing the toilet during or shortly after a shower.

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    If there is not good venting in the system then the water from the shower draining away (particularly if it if falling vertically in the pipe) can creates a suction. This can alter the air pressure on the drain side of the toilet and suck the water out of the bowl.
    – Ukko
    Sep 20, 2019 at 19:27

Sounds like a partial blockage in the outflow pipe and a blocked vent stack.

As the sewer fills with the water from the shower (due to it being partially blocked the water cannot quickly escape sosit floods) the air displaced by the water which air would normally escape through a vent (such as the vent stack) is not escaping, this causes an in overpressure in the sewer, and behind the trap in the toilet, raising the water level there.

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