Caulking everything to stop a leak?

Your tub is leaking SOMEWHERE... how do you find out where?

One of our friends, Gregg Jarit, contacted me the other day on a topic I've heard many times before, but with a little twist because TWO bathrooms are potentially involved:

"Miles, a few weeks ago we noticed a wet spot on the wall of the bathroom on the main floor, which is under the kids bathroom. I'm concerned that there is a pipe leaking somewhere under the tub or coming down the wall. I'm curious as to your thoughts and how to accomplish the diagnosis and fix. My father added caulk around the drain to see if that could be the issue. He also wants me to go in the attic and see if it's coming from the roof, but I highly doubt that. I wasn't even sure who to call (plumber, contractor, etc). Thanks, Gregg"

Although we have two bathrooms here, the problem can be determined with some patience and a methodical approach-- I call the following procedure “shower fault isolation”. It helps determine if we have a pipe leak requiring a plumber, or something simpler:

1) Remove the cover plate of the tub drain. Place a garden hose into the drain pipe and run water into it without splashing water into the tub. Run the water for about 10 – 15 mins. See if a water spot appears. If yes, then it is a leak in the trap or drain pipe. If no, then continue.

2) Put back the cover plate on the tub drain. Wait at least an hour to make sure a wet spot from the previous test does not appear. Run a hose in the tub for 10 – 15 mins. Check for water spot. If yes, it is the seal around the drain / tub. If no, continue.

3) Run the bathroom tub spout for 10 – 15 mins. See if a water spot appears; if yes, then it is the pipe between the shower faucet and the tub spout. You If no, continue.

4) Run the shower head only in the tub, do not get the walls wet. See if the water spot appears; if yes, then it is the pipe leading from the shower faucet to the shower head. If no, continue.

5) Spray water on one wall of tiles at a time. See if the spot appears... it most likely will. If yes, then it is the caulking or grout on that wall-- a relatively easy "do it yourself" fix.

With a little time, you can find out the problem and know what you'll need to do. Hope this helps, Gregg!