Finding a leak

[Matt Melton]

I have a leak that I cannot find the source. I removed the drywall on my ceiling and see a drain pipe above the spot I found wet. It goes to the back of the tub. What could this be connected too?

I have attached pictures to better show my question. I appreciate any help I can get.

Sincerely,
Matt

 

[Terry]

That wye with 45 may be the vent for the tub. Sometimes that also have something like a lav tied into that too.
You need the vent to prevent the tub trap from siphoning.

Water will flow to any low spot. Sometimes you need to follow the path.

 

[Sponsor]

 

[Reach4]

Note if you see more dripping following a rain.

 

[Matt Melton]

That wye with 45 may be the vent for the tub. Sometimes that also have something like a lav tied into that too.
You need the vent to prevent the tub trap from siphoning.

Water will flow to any low spot. Sometimes you need to follow the path.

I guess it must be a vent because the lav is off to the side a bit. I guess I will just have to check for the leak source. Have you ever used food dye to color water and find a leak?

 

[Reach4]

I guess it must be a vent because the lav is off to the side a bit. I guess I will just have to check for the leak source. Have you ever used food dye to color water and find a leak?

I have not, but it sounds like a good idea.

I have put dye into a gutter drain to see where that water went. That dye was made for the purpose. But food color is easier to get locally.