We live in LA and it rains every once in awhile. I noticed recently that there is a bubble on my wall and I can actually push it around. The wall is plaster and we have latex paint on top. (There are many layers, b/c this house is 90 years old, so the bottom layers may be other kind of paint.)

I know that eventually I will have to fix where the source of the water leak is, but I. The mean time can I just pop this bubble by making a tiny pinhole to drain it? Or is it a bad thing to do. I don’t want the hole to grow bigger.

Here’s a picture. I’ve placed my hand next to it for scale. water bubble


I wouldn't be inclined to make a pin hole because it could take too long to drain and could be soaking into the wall and forming mold. I'd make a small slit right on top of the baseboard. Now you really need to find the source of the leak. Is that an outside wall?

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  • The slit will also be easier to hide later – Ack Apr 3 at 23:28
  • The other side of the wall is the outside of the house. – milesmeow Apr 4 at 1:55

Once you've cut it open and determined it's water and not an air pocket the hard work begins. Since it's an internal wall it probably is an in-house leak but not necessarily. Obviously, you'll want to track it down with a minimal amount of cutting out drywall. It's possible but unlikely that it's a leak from a pipe in the wall. The odds are that it's a bathroom leak or from an exterior source (roof, vent, etc). So start with the obvious.

You've probably checked other walls already. If you haven't found anything check under bathroom sinks and showers that are above that area or immediately adjacent. Water will travel a long way across ceiling joists before soaking through or running down a wall so start in close and work your way out.
You can purchase moisture sensors on-line for about $50. It will help to sense damp areas in your home and might help you track down the problem. If you don't find anything obvious you'll probably have to cut out some of the drywall to see where it's coming from.
I would start directly above the wet area cutting a hole large enough to get your arm into. Feel up and down for moisture. Use a moisture meter if you have one.
Remember, it's usually something simple rather than something commplicated. enter image description here

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  • It’s probably from an exterior leak... such as from the roof. – milesmeow Apr 4 at 1:53
  • Glad you could narrow it down quickly. – HoneyDo Apr 4 at 3:27

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