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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    Those look pretty scary. Are there any cracks on the bottom of the toilet in that same area? – JACK Oct 17 at 1:02
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    @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 Oct 17 at 7:51
  • Can you contact the manufacturer and ask them? – Steve Wellens Oct 17 at 14:27
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    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 Oct 17 at 18:11
  • Is the toilet siting on a flat level surface or uneven tile ? – Alaska Man Oct 17 at 20:53


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.

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    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 Oct 16 at 20:20
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    The location of the cracks is especially worrying: three of them are radiating from stress-concentration points. – Mark Oct 17 at 0:11
  • Definitely agree. It's not worth the risk. – JACK Oct 17 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. – whatsisname Oct 17 at 1:59
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    Yeah, the thought of sitting on the floor with porcelain shards in my butt has crossed my mind. – Mattman944 Oct 17 at 7:53

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