Im pretty sure this is where the water is settled and where it drips through the ceiling on main floor looking through the access wall.

That shower only pattern is a big clue. Since it does not happen with a bath, I would look hard at the shower drain connection and the pan or tile grout before assuming it is a supply line. Water can also travel along a joist and show up well away from where it gets in, so the dry spot behind the wall does not rule out the shower. One test that helps is running the shower with the drain plugged for a few minutes, then unplugging it, to see whether the leak follows the standing water or the draining water.

Thank you! I will give it a try.

You will also need to do some serious work in that area as you have some fairly serious water damage there and what you cannot see will most lilely be worse. That much water damage leads me to think something has been leaking for quite some time. I am afraid you are thinking bandaids when you will need surgery.

Yes! im thinking rip out the tub, all surrounding tile and replace everything. At this point probably a total renovation. grrrr Thank you.

Marie, I understand the frustration. Before deciding on a full tub and tile renovation, I’d first have a plumber or qualified bath professional observe a controlled shower test through the access opening and isolate the supply, drain and water escaping the surround. Since showering triggers the leak, avoid using it until the source is found.

If the ceiling is opened for inspection, have the wet materials and any visible damage assessed and dried before closing it. A full renovation may make sense if the surround or concealed materials are compromised, but identifying the entry point first helps prevent the same leak from returning in the new work.

I have the ceiling open where the leak is and its the subfloor its dripping from. any pipes i see in the opening in the ceiling aren't leaking from what I am seeing. That makes me think its coming from the tub somewhere. I thought forsure replacing the water knob, faceplate and cartridge was the answer along with the tub spout. process of elimination. Now im puzzled. if worse comes to worse I will take out the tub and replace it and anything else related. Thank you! Since i am not getting water on the floor i highly doubt its leaking at the side of the tub to the floor below. i did buy a scope camera and may drill a few holes and see what i find. Just a woman determined.

That subfloor detail is helpful. If the pipes you can see are dry, the water is likely running along the subfloor from somewhere else in the shower area before it drips through. Does the wet spot line up closer to the drain, or to the wall where the shower spray hits? That would help narrow down whether to look first at the drain area or at the wall and grout joints.

The wet floor spot is more at the outer edge of the tub. And on the end of the tub with all the fixtures.

I work with QUAY Construction, a renovation contractor in Vancouver, so I'm seeing this from the rebuild side. A wet spot at the fixture end that only shows up with the shower points to two places for your scope camera: where the valve and spout come through the wall, and where the tile meets the tub at that end. Shower water hits those joints and a bath doesn't. New caulk only seals the surface, so water that gets behind the tile can run down to the subfloor without ever reaching your bathroom floor. Before tearing everything out, tape plastic over that end wall and run the shower. If the ceiling stays dry, the water is coming through the wall. If it still drips, look at the drain next. If you do end up replacing the surround, here's how the main waterproofing systems differ: https://quayconstruction.ca/blog/bathroom/best-shower-waterproofing-systems-2025-costs-expert-review/

That fixture end detail helps a lot. I'd check the valve and spout connections behind that wall first, since a slow drip there will run along the subfloor and only show up when the shower runs.

I did check the valve and replaced the cartridge. Tested it for leaks prior to putting the new faceplate on with handle and it was dry. Also replaced the spout that has the pull up knob to shower. Honestly i dont love it since the internal parts are plastic and may change that out again when i find a better one. I will try some of the other test suggestions you have offered. I appreciate all of your suggestions, ideas and professional comments. I may even open up the access I cut out in the wall bigger and get in there better, move that insulation so i can see more at the bottom. Thank you

Good, that rules out the valve then. Opening up that access a bit more is worth it, you really want to see the bottom of the wall and the drain area when you run the shower.