Is a Wet Spot in The Ceiling From Toilet Plumping?

Question

My home is two stories and in a first floor room the has a wet spot. Deduction reasoning points to upstairs toilet as the source. And, if I turn off water to the toilet and stop using it then the water spot dries.

To be able to use toilet again, do I just replace the toilet? Is it the a problem with the waste line that runs from the toilet and it no longer leaks because I am no longer using the toilet?

I know basic plumbing skills so I think I can make repair on my own.

EDIT

The tank is empty, water line is cut off, should I flush one more time to remove the water from the bowl (is that the right word for it)?

Answer 1

You are going to have to do some testing. The first thing to do is assess how likely it is that you could have water in the bathroom from spillage. If water isn't running into the toilet area - from people showering or washing hands/whatever - then you might as well pull the toilet up.

To pull the toilet you will have a bolt on each side (undo the nuts) and a water supply line (turn off water and disconnect by unscrewing. Once water is turned off flush the toilet to get rid of as much excess water and then pull it up.

Now you will need to assess what things look like and you may need to provide pictures to us. There are several reasons a toilet would leak. The first and easiest thing to do is dump a bunch of whatever down the toilet pipe. It is highly unlikely that you have a leak there but this is super easy to check. Do this first.

Next assess how the toilet flange looks and how high it is. It could simply be that the toilet release is a bit too high and that over time the flange plus wax ring degraded enough to cause a slight gap. This is most likely your issue.

If the flange is worn, brittle, or cut then replace it. If the flange is good but too low you will need to replace it with a flange that sits higher. This is an easy job and just takes a few minutes.

If the flange looks OK height-wise and what fixes 90% of toilet leaks is replacing the wax ring. Since you have a leak I would suggest an extra thick ring.

(I didn't mention everything but covered what should help 95+% to make it easier - let me know if you have more specifics questions or pictures)

Answer 2

Locating the exact cause of a wet ceiling spot does take some detective work and may even entail opening up some of the drywall. It sounds like you have made a very good first step with the investigation by noting what happens when the toilet was shut off.

I believe that you still need to do some more investigation before just jumping to the conclusion that you need to pull the stool and replace the stool seal. You could just as well have a slow drip leak associated with the water closet (tank), its fill valve or the tank to stool seals.

If the toilet has been installed in the place for many years it may very well be a worthwhile exercise to pull the whole toilet and inspect and then replace all seals, fill valve, flapper, and stool seal. If you do that also consider replacing the line from the valve to the toilet tank with a new one. Especially if it is one of those flexible types that can degrade after years.