Ceiling Plumbing Leak Repair
This ceiling was damaged by a water leak from a plumbing
supply pipe. Now don't get confused with the black pipe and the rust
spots on it. This could give you the illusion that the water leak is
coming from the waste pipe and not from the water supply pipe above it.
Home Repair Tip: When looking for water leaks, try not to look at the obvious. You might find rust or corrosion around a pipe or metal flashing and your first response or thought, would be that you have found the problem but in reality, the water is leaking from another spot. Often somewhere above the corrosion.
In a situation like this, where you are assuming that the water leak is coming from the black waste pipe, simply run some water through the waste pipe and watch for leaks. Sometimes the water leaks will be coming from spots with rust and corrosion, but don't assume that you found problem, when you're looking at corrosion on metal pipes or flashing.
I'm mentioning this, because I'm the one they call, when the ceiling has been repaired but the water leak hasn't. Save yourself some frustration, by locating and repairing the problem before repairing the ceiling.