We have an old bathroom (circa 70s we think) which has a toilet that is draining slowly to empty. The internet is not being fantastically helpful here as googling for a "slowly draining toilet" only finds posts about flushes draining slowly - whereas this one is emptying out the bowl over the course of a few hours.

For all I know about toilets - my suspicion is that somehow the U-bend just out of sight has a crack in it that is allowing the water to circumvent the U-bend and drain straight down. But I am unsure how that would occur - the rest of the toilet is apparently undamaged.

Is my suspicion likely to be correct? I've found a couple of other questions similar to this on DIY but its a bit hard to tell without pictures if its the same issue. Is there any way to check that suspicion without having to get a plumber or a colonoscopy camera in there?

The rest of the toilet is a solid ceramic construction, so there is no visibility of the U-bend from the outside. We are also the landlords here having moved back in after ~15 years of leasing - so we aren't sure if the previous tenants potentially did something a bit dumb with the plumbing.

Before draining Text

After draining Text

  • 4
    Sounds to me like a plugged vent, letting suction on the line draw water downward... Assing the water doesn't seem to be going anywhere else.
    – keshlam
    Feb 14, 2023 at 21:53
  • Yeah, check the vent terminations and then pull it out and have a look. We can't help much beyond that.
    – isherwood
    Feb 14, 2023 at 21:54
  • 3
    Get a toilet snake and route the toilet out. You might have something lodged in there that wicking the water over the U bend.
    – JACK
    Feb 14, 2023 at 21:59


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