a rental toilet has a dark clay looking stain in the bottom of a toilet that the renter was unable to remove. At first I thought it was very hard water, however, there was no evidence of stains in a second bathroom or any other fixture. There is evidence of cat litter in the area and I was wondering if cat litter could form a tough clay layer in the bowl? Also, if cat litter is in the toilet, could it be in the drain piping and be a problem waiting in thwings. Can anyone suggest a way of removing from the bowl?

  • On the chance that it's actually rust and/or minerals, try turning off the feed valve and then flushing to empty the bowl. Then see if CLR makes a difference. You can lay paper towels against the bowl, wet them with the CLR, and let them sit for awhile (the paper towels will hold the CLR in contact with the stain). After maybe half an hour, use the paper towels to wipe the stain and see if it comes off. If it lightens it but doesn't completely eliminate it, repeat the process. – fixer1234 Jun 20 '17 at 18:59

My mother had a cat and dumped the cat liter down the toilet. At 90+,She would sometimes forget to flush the stuff and it would cake like that. When I would find it I would use a stick to dislodge what I could, and After much use it would dissolve and be gone.


Cat litter is typically bentonite clay, so even if it has settled to the bottom & stuck to the surface it should be possible to remove it as it won't harden & set while under water (unlike cement).
I'd try using some sort of hard plastic spatula-like impliment to scrape the bulk off, followed by a vigorous scrub with a stiff-bristled toilet brush.
As for the rest of the drain plumbing ... if it is clay cat litter and it has settled somewhere inaccessible - you may well have a potential problem brewing.
You probably won't know until something gets stuck somewhere (or you go to the trouble of pushing an inspection camera down the pipes).


If the toilet is older, maybe it does have hard water build up because the porcelain isn't as protected as the other..more porous possibly from years of abrasives. Just a thought. I have the same issue and will try Fixer1234'method.

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