My upstairs toilet is leaking into the ceiling downstairs only when the water supply is turned on. One company came out and cut a hole in the ceiling and said it is not the water pipe. Another company came out pulled the toilet and changed the ring. The toilet is still leaking. It is a slow drip like a drop every 20-30 minutes. What could cause this?

  • Have you checked out the shutoff valve for the toilet... the valve coming out of the wall?
    – JACK
    Commented Feb 11, 2021 at 22:55
  • When you say "only when the water supply is turned on", do you mean that with the supply stop-valve next to/behind the toilet turned off, it does not leak? Or are you shutting off more of the system, like shutting down water supply to the pipes in the wall that lead to the toilet? This is an important trouble-shooting detail... Commented Feb 11, 2021 at 22:57
  • Tank, bowl or pipes/joints are three places to check. Slow drip, upstairs, might want to check for condensation.
    – crip659
    Commented Feb 11, 2021 at 23:03
  • Yes, the water shut off that is connected to the wall behind the toilet, that stops the water from allowing thank to fill was turned off and the leak stopped. Water can be in the tank but the leak doesn't start until the water is turned back on behind the toilet.
    – Lisa B
    Commented Feb 13, 2021 at 1:12
  • Sorry forgot to add it leaks in the wall not on the floor in the bathroom. Never any water on the floor of the bathroom. It runs down the pipe and intro the ceiling of the kitchen downstairs. Since there is now a hole in the ceiling you can see the drip.
    – Lisa B
    Commented Feb 13, 2021 at 1:15

2 Answers 2


Common problem, you have unfortunately been cursed with a series of maroons since fixing a leaking toilet is about the easiest handyman job there is.

My guess is you could do a better job fixing it than the buffoons. Turn off the water, wipe up all the drips and such behind the toilet so that everything there is clean and bone dry, then turn the water back on and lay back with your head behind the toilet for 20 minutes staring at the plumbing. Eventually you will see a little bead of water forming somewhere that is where the leak is. My guess is it's the valve stem seal but there's plenty of other potential areas. Feel around on the pipes with your fingers. Water leaks like to happen behind pipes and such where you can't see them and water likes to travel down away from the actual source to make it harder to find the leak. You can't find these leaks by just staring at pipes you have to get your fingers in there and feel around.


So the copper water pipe in the ceiling has been confirmed to be not leaking.

A new wax ring ensures the toilet horn (waste line) is sealed tightly to the closet flange.

The only other possibilities are a cracked porcelain base or a dripping shut-off valve or supply hose.

Check the base first by trying to lift one side and then the other of the toilet. It should be un-moveable in any direction. If not try pulling the threaded studs that hold it to the closet flange (floor). These should not be moveable ,too. If they are extremely loose or free the closet flange they are attached to may have broken and needs to be replaced.

If the studs are slightly loose you can try tightening the nuts slowly until they are snug. Use a level placed on the bowl rim as a guide on which nuts to tighten first.

Also, with a flashlight verify that there are no hairline cracks at the base of the toilet which could mean a leak.

Also, with your hand feel along the supply hose at both connections for any wetness which would mean a connection needs tightening.

The nut on the bottom of the reservoir that holds the flush valve in place may be loose.

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