I have a leaky tank problem with my upstairs toilet. can I turn the water supply to the toilet? If so, how do I turn off the toilet water supply?

  • You might not have to turn off the water - you can sometimes just tighten the bolts holding the tank to the bowl. Don't break the tank!
    – Ariel
    Jan 8, 2015 at 17:34
  • 4
    Probably not a great idea to try if you don't first have a way to turn the water off in the event the tank does break.
    – Steven
    Jan 8, 2015 at 19:34
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    @Ariel it is better to drain the water, dry off the gasket, and tighten back down. If any water is in that gasket it might not seal properly and may continue to leak even if torqued down enough to stop leaks otherwise.
    – user4302
    Jan 8, 2015 at 20:58
  • @Snowman I don't believe that's true. Gaskets do not care about water - if anything the water acts as a bit of a sealant and lubricant.
    – Ariel
    Jan 8, 2015 at 21:06
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    @Snowman I understood what you said, I simply don't agree. Although it's hard to argue against your experience, I believe the fix was because you redid it, not the lack of water. From my experience adding fluid to a seal helps because it fills in the tiny little crevices and texture.
    – Ariel
    Jan 8, 2015 at 21:34

2 Answers 2


In almost all cases there should be a shutoff valve behind the toilet, just follow the visible pipe that comes out the bottom of the toilet tank. It will either be a globe valve that has a handle you need to turn many times to open/close, or a ball valve with a handle that you turn 1/4 turn to turn on/off.

If there is no shutoff valve, you would need to turn off the supply to your entire house. It would also be a good time to install a dedicated shutoff for the toilet.

  • 2
    And if you find a valve that takes many turns instead of a quarter turn don't be surprised if it doesn't work. Every single such valve the builder put in here failed on at most the second use and I replaced it with a quarter-turn type. Jan 9, 2015 at 3:11

On a toilet installed up tyo code here in the united states there is a valve located under the tank behind the toilet. Turn clockwise to turn off water to toilet. Flush toilet and be sure it does not fill the tank again just to verify and empty most of the water. Where is the leak coming from exactly? It could be leaking from several places

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