Hello all,
So I live in an upstairs apartment in what I believe is a house that was converted into 2 apartments, an upstairs and a downstairs. The downstairs neighbors have been having problems with something leaking in their bathroom wall causing a "tumor" in the wall that was filled with water. In response I put up more shower curtains to make sure that I wasn't leaking water out of the shower. The landlord claimed that he had caulked the side that was leaking. It happened again and I am wondering if it could be pipes or something more significant. I looked at the damage and it wasn't under our shower it was off to the side and under where our toilet is.
Any help on the mater would be great as I'm afraid of getting charged for damages.

Tell us something more about your shower: what kind / type is it ? Tile ? Plastic ? Also, what kind of shower pan ? Tile ? Plastic ?

Perhaps, you can snap few pix and post it for us to see.

Back to you . Milo

If it were my home I'd have the ceiling down already in the lower unit. That likely must be removed to repair and the walls are soaked and must be dried and cleaned. There is mildew growing but you can't see it. Unfortunately your LL does not appear to know what to do and its really isn't your issue. The tenant below should be after him to properly fix it. The list of possible causes is long and will not get shorter until the ceiling is down

Bob's bang on! Before a leak can be repaired you must first locate the source. Open up the ceiling and Run the shower. Now check the base of the trap. If it's wet then it's s drainage leak. If it's dry then the water's getting behind the shower wall. Let me know, Tom

DO NOT remove any ceiling, that is your Landlord's issue. Since this is not your apartment, any damages from leaking into another unit or side is not a liability to you as long as you did not directly cause the leak. Your responsibility is to notify the LL and let him fix it. The complaint should be from the person having the damage. I know you want to help things along but anything you do could possibly considered aggravating the issue.

Good catch Brian!