I recently noticed water in my closet on the back side of my shower.

The leak seems to only occur when the shower is running.

I opened the walls and there was no water coming out anywhere except the very corner. The pipes are all dry.

I had a plumber out and he said there isn't a leak, that the water must be weeping through the grout. He suggested I get someone out to seal all of the grout.

Being a bit skeptical, I put the water hose over the drain and ran a lot of water through, but there was no sign of a leak.

I have now ruled out the drain, the supply and the lines between the supply and the shower head.

My shower is about 8 years old and is sealed granite. Should I have the grout sealed or is this a long-shot?

If it's not the pipes, then yeah getting the grout re-sealed can't hurt. Before you do that though you might try re-caulking around the top of the tub as it'll probably make a world of difference. Speaking of which I need to do that to my own tub, blah.

Take it as good news, new caulking is way cheaper than new pipes, resealing the gout might be a bit more, but it's still better than a leak in the wall somewhere!

Random thought: have you tried spraying only parts of the tub/shower to try and figure out where exactly the 'leak' might be?

Gernald is right! And by the way, sealing grout and stone is very, very easy to do. Follow the directions and get years of satisfaction. But you should probably do it a little more often.

You said, "I opened the walls and there was no water coming out anywhere except the very corner"

Can you explain this in greater detail?

Mark

There was no water on the pipes, no signs of water anywhere-- no drips, no condensation. I really couldn't find any sign of water, except...

In the floor, in the corner (this would be in the closet, where the back of the shower wall meets the exterior of the house) the concrete floor started to become wet. There was no way to tell where it was coming from, as I couldn't open that area without ripping out the exterior stucco or the inside of the shower.

I'd eliminate the shower pan, first! Here, remove the shower drain strainer and stuff a plastic bag with socks ans stick it down tight into the shower drain. Now, using water from another source (say a hose from an outside faucet) fill the shower pan to the level of the threshold.

Let that sit for 12 hours or so and periodically check that corner for leaking. If the leak shows up, then most likely you have a leak in the shower pan. If no leaker, then regrouting/sealing is the way to go!

Mark