We recently replaced a toilet and are noticing a recurrent, slightly yellowish stain in the bowl, which I can easily clean with a little soap. It's a ring around the bowl about an inch wide, right above the surface of the water. The new toilet is white while the old one was a fairly dark color so I don't know if this was always happening but went unnoticed.

I attach a photo which has been processed somewhat in order to make the stain more apparent.

Of course since the stain is yellowish it's easy to associate it with one thing in particular but there is clean water in the bowl >99% of the time, so what could be causing this?

Toilet Stain

1 Answer 1


Rust in the water.

If you have steel or iron pipes, they might be rusting out in the inside.

If you have any other types of pipes, it may be coming in from the city water.

If you have a water softener, get salt that's also labeled as a "Rust Remover", if you don't have a softener, consider getting one.

  • We only have copper or Pex in the house. No water softener. Why would the stain be located just above the water level in the bowl and not more present all along the sides? Commented Dec 17, 2023 at 20:01
  • 2
    Because just above the water level is where the water evaporates away, leaving just the particulates. Below the water level, the particulates stay in the water. Farther above the water level, the water (with the particulates) flows down. Incidentally, my house has pretty much all copper or Pex, but there was also a steel "nipple" in the bath piping that rusted. Now there's a brass version. So check the piping to and inside the toilet. You also may want to get water samples from various places and send them to a testing lab (possibly at a university) for analysis.
    – mdfst13
    Commented Dec 18, 2023 at 3:34
  • CLR will probably remove the mineral deposits on the bowl from the water which get stained. Household vinegar might remove it but probably not. Commented Dec 18, 2023 at 19:34

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