I just noticed these cracks in the bowl of my toilet. It is not leaking water. Can I assume that these are just cosmetic cracks in the glazing? Or, should I worry about a catastrophic failure?

I installed this toilet myself about 20 years ago. It is on tile over a concrete slab; it is solidly mounted, there is zero rocking. It is an expensive pressure-assist toilet so I would rather not replace it.

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Edit: Found a crack on the outside.

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Edit 2: Finally got my replacement toilet (special order and they got the order wrong the first time). Pulled the old toilet, now I can see the underside.

There is a crack, but the location doesn't match the top bowl cracks. What is most interesting is that it looks like glazing was added during manufacturing. I am guessing that during inspection they noticed some tiny cracks, and rather than scrap the toilet, they tried to repair the cracks with glazing and re-fired the toilet.

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  • 2
    Those look pretty scary. Are there any cracks on the bottom of the toilet in that same area?
    – JACK
    Commented Oct 17, 2020 at 1:02
  • 1
    @JACK - looked more carefully, found a crack on the outside, see edit. The toilet is in an alcove, so it is not easy to see.
    – Mattman944
    Commented Oct 17, 2020 at 7:51
  • Can you contact the manufacturer and ask them? Commented Oct 17, 2020 at 14:27
  • 1
    The exterior crack does seem to lead to the bolt hole, suggesting that it might have been just a wee bit too tight and started cracking there. It's a difficult judgment call, and even plumbers get it wrong sometimes. Too loose and it moves, too tight and it cracks.
    – Ecnerwal
    Commented Oct 17, 2020 at 18:11
  • Is the toilet siting on a flat level surface or uneven tile ?
    – Alaska Man
    Commented Oct 17, 2020 at 20:53

1 Answer 1



There's no reason for "cosmetic surface cracking" 20 years on that doesn't come with sub-surface structural issues. Something is not right in there, and it will come apart one of these days - tomorrow or 5 years on, we don't know, but it's likely to be inconvenient, messy, and quite possibly involving an embarrassing trip to the emergency room for cuts sustained in the failure.

  • 1
    I agree. While it's feasible that the cracks are cosmetic there's really now way to be even somewhat confident in that fact.
    – isherwood
    Commented Oct 16, 2020 at 20:20
  • 1
    The location of the cracks is especially worrying: three of them are radiating from stress-concentration points.
    – Mark
    Commented Oct 17, 2020 at 0:11
  • Definitely agree. It's not worth the risk.
    – JACK
    Commented Oct 17, 2020 at 1:02
  • Given the fixture it's also pretty much guaranteed to fail precisely when you're suffering food poisoning from the dodgy greasy spoon diner. Commented Oct 17, 2020 at 1:59
  • 6
    Yeah, the thought of sitting on the floor with porcelain shards in my butt has crossed my mind.
    – Mattman944
    Commented Oct 17, 2020 at 7:53

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