Bathtub leaking into apartment below

I own a 6unit apartment building. When the upstairs shower is used, the ceiling of the bathroom immediately below drips. I opened up an access panel below to verify. The only times it leaks is when the shower is used.... not when the water is coming out of just the spout for a bath. All the caulk looks good, drain below looks good. Anything else it can be than besides the pipe going from the valve body to the shower head? Its a Union Brass/Union Gopher 2 handle deal. Thanks!!

Remove the shower arm and apply 4 wraps of teflon tape and reinstall. Then see if it still leaks.

Do you have a plumbing access panel? If not, I would strongly suggest making one. If you can actually see that the shower arm or riser pipe is leaking (or not) it will make your diagnosis much easier. If it is not a plumbing leak, then it is a leak from your tile/grout/caulk, etc..

if it is a single handle valve remove the trim plate, then you will see if it is leaking from the riser. If you have a diverter spout it is most likely the nipple for the tub spout. When running the spout there is little pressure on it so it leaks little enough to make it unnoticeable. when you divert the water to the shower the added pressure makes it leak considerably more. Don't know why people use galvanized nipples there, it is a leak waiting to happen, although it takes many years.

I've see so many calls like this and so many times it's water getting through the wall at the faucet or spout. But then you find it leaking through the floor, the customer says , but we don't get water on the floor. You need to look in the access and prove the point. Showers can get water over on to the floor and you don't see a puddle. Can do it with a shower curtain or a shower door just the same. Sooo, check real good.

And when you leave, you have to make sure the tenant will be very careful and keep the water inside the tub.

Again an access door allows you to see all the tell tail signs of water that has gotten out of the tub.

I looked into it a little more. I removed the bezel off the cold water stem and found it dripping. I replaced the o-ring that went between the stem and valve body and looks like its OK now.

greekguy7 said:

I removed the bezel off the cold water stem and found it dripping.

Click to expand...

Interesting choice of words. Were you in the jewelry business at one time?

I guess its really called a flange, not a bezel. The part that was actually leaking is called a cap gasket. A new cap gasket did not come with the stem assembly when I replaced it a couple years ago so I probably used the old cap gasket. The cap gasket goes between the valve body and the stem where the two mate