We have a dripping noise coming from the upstairs bathroom, that we hear in the ceiling of the room below. It drips during and after we shower, but there is no water damage on the ceiling. We even checked the recessed lights and the fan/vent in the downstairs bathroom, and there's no water! It only happens when water goes down the drain, as we tried pouring water down the drain from a bucket. The upstairs bathroom is new, with PVC pipes, and was part of an addition to the house. Downstairs is some new plumbing, but I don't know if all of the pipes were replaced or not. Any ideas as to what might be causing the problem, or how I can avoid tearing up a new bathroom floor?

What type of shower do you have? Custom tile or a manufactured shower base and enclosure? If the latter does the floor give a bit when you step on it?
The first thing you must do is to localize the leak. Remove the strainer and pour a few pitchers of water down the open drain being CAREFUL TO POUR IT DIRECTLY DOWN THE DRAIN AND NOT GETTING ANY ON THE SHOWER FLOOR. Do you hear a drip? If so the leak's in the trap or drainage line.
If you don't hear a drip now close off the drain hole with a plug or just blow up a balloon in the drain to seal it off. Now fill the shower floor with a inch of water and listen. Is it dripping now? I have no idea where the water's going but I think I know how to stop it. Get back to me with the results and I'll tell you. Regards, Tom

Thanks for your response! We have a tiled floor shower. Last week we were trying to rule out possibilities, and we poured water directly down the drain, as you suggested. That's when we heard the noise. It is a dripping sound that speeds up when the water's going down the drain, and slows down and stops as time goes by. It probably lasts 15 min to a 1/2 hour, depending on how long the last shower was. Does that help?

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Originally Posted by Nadelkramer

Thanks for your response! We have a tiled floor shower. Last week we were trying to rule out possibilities, and we poured water directly down the drain, as you suggested. That's when we heard the noise. It is a dripping sound that speeds up when the water's going down the drain, and slows down and stops as time goes by. It probably lasts 15 min to a 1/2 hour, depending on how long the last shower was. Does that help?

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It helps me but not you. I was hoping this could be repaired without opening up the ceiling but you have placed the leak in the trap or drain connection.
Now you have no choice but to open up the ceiling, pour water down the drain and pin-point the source. Let me know what you find. Regards, Tom

Better the ceiling than the tiled floor I suppose? Thank you for the help. I will let you know the outcome.

So, I had a pro come out, because I felt out of my league. For the first 1/2 hour, we couldn't make the noise happen at all. He checked all over the house, and couldn't find any evidence of a leak, or water damage, even behind the little compartment that allows access to the pipes. As he was about to leave, I hurriedly poured water down the drain from a bucket. Unfortunately, I wasn't careful, and water also went onto the floor of the shower. In any event, that worked, and we were able to hear the noise. He says that the pipes are very tight in the joists, and it could be the sound of expansion of the pipes in this tight space. Otherwise, there is a leak, likely in the connection between the pipes (apparently in looking at other pipes in the house, there is not "purple stuff" around the PVC joints).

Last night, though, I heard the noise upstairs too there's no bathroom above that one). I also occasionally hear a small "bang" or "settling" noise in the same bathroom. I would have to imagine this is related?

For now, I think we're going to opt for the "wait and see" approach.