Determine source of water leak

Question

The issue is that water is dripping onto ceiling tiles.

The photograph shows a concrete ceiling embedded with a 3 inch PVC pipe. It would seem that the leak is above the concrete ceiling as the concrete ceiling is wet. Once the leak has been plugged the ceiling tiles will be restored. Approximately 4 ounces of water drips in a 48 hour period.

The blue pan is placed underneath the leak to collect the water.

There are 2 other very similar pipes that pass through the concrete ceiling, which are not leaking. There are two bathrooms in the apartment above and it would not surprise me if these three pipes are drains for either sinks or toilets.

Is there a clever technique that can identify exactly the exact leak of the pipe? Preferably without breaking any concrete.

Answer 1

Yeah, those side branches do look like they could serve toilets. It seems quite unlikely the repair would involve breaking any concrete though.

Somebody will have to gain access to the space above to find out how the water came to be on the top side of the concrete. Supposing there's a toilet up there, I'll guess the toilet needs to be removed from the floor and the wax ring or gasket replaced.