I have a very slow leak somewhere around the plumbing access to my shower/tub that I’ve been chasing for some time now. I’ve been placing a 12oz ‘Tupper ware’ container just underneath and between the shut-offs. I check it once a week and it fills up about half way. I replaced the shower valve due to some water stains around that, but that doesn’t seem to be the culprit. I’ve sat and watched the access area while my wife showers, but don’t see any drips. Any one else have any other ideas?

I’ve recently place a plastic sheet in the wall between the shut-offs and the area where the tub wall and tub meet… to try and pin down where the leak is. My thinking is if my container has water in it in a week, it will mean the shut-off may have a very slow leak in them. If there is no water in the container, then maybe I need to re-caulk where the tile and tub meet (no obvious cracks there now.) Any other methods to determine where the leak could be?