I have a leak developing in my ceiling that is coming from what I assume to be the upstairs bathroom. This first happened when my pipes needed to be snaked a bit over a year ago where, during that, the water supply to the house was shut off. There is a nice little bubble in the drywall from that first time, but I let it go since it hasn't leaked since and it's in a room I currently am not using.

SO.... when I got home last night the cold water in the upstairs shower would not shut off. I turned off the house's water supply, got a new valve this morning and replaced it... BUT when I came home from the hardware store (water supply has been off all night/ morning) I heard that familiar DRIP DRIP DRIP and ran to the back room where the ceiling was leaking a LOT... So much that it proceeded to go through another level into my basement. There have been no leaks for well over a year and it HAS to be because the main water supply was turned off. It never clicked with me about the first time this happened that it was not a slow leak but maybe a pressurized leak?

Is the best thing to do to remove the drywall around the bubble and see if the culprit is directly above or are there some other things I can/ should be checking? I know that I will need to replace the ceiling either way at some point, but I don't want to bother until the source of the leak is found.

Most suggestions that I have found are for leaks when water supply is on... so I am not certain where to start since this is only a problem when the water to my house is shut totally off.

Thank you!

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    Cut open the drywall ceiling near the location of the leak and keep cutting until you find it. Your description of events may seem to make sense to you, but to someone familiar with plumbing it seems likely that there has been some sort of unfortunate coincidence of events. Commented Aug 8, 2015 at 23:42
  • What material is the pipe made of? You may have overflexed some glue if it's pvc; or solder if it's copper. Even lead and iron eventually corrode, usually around fittings. You've got to get in there to see. My SawzAll works well on drywall or plaster and lathe. You'll have a heck of a mess to clean up though. Use lots of tarps, as either powder likes to hover in the breeze. Commented Jun 27, 2018 at 22:59

2 Answers 2


Maybe someone hit a drain pipe when drilling a wall anchor? That it only happens with the water off is odd, I'd just focus on finding the leak. The water is coming from somewhere.

I'd start by opening up any access panels you have to the upstairs shower. You're looking for blackened wood where the pipe enters the floor in the wall.

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You're probably going to have to replace the drywall around the ceiling spot, you might as well open that up too. Try to drain the bubble by poking it in case it still has water in it. find the vertical source of the water that way- though occasionally water travels horizontally.

Follow the water. You make enough holes in the wall and you'll find the source.


So the bubble on your drywall is just the final destination. Water doesn't manifest from nothing. Its likely you have some kid of reservoir formed elsewhere in your home and the water is flowing to that spot on your drywall. start at the bubble and find your way to the source. if you wait long enough the leak will stop.

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    They usually stop voluntarily only in areas with hard (300ppm+) water. Sometimes that can take a year or more though. He may have caused the problem by disturbing an internal CaCO3 coating on the piping when he let the water drain. Commented Jun 27, 2018 at 23:08

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