Both of our bathtubs (one upstairs & one down, both in same part of house) will occasionally leak when we drain them. The upstairs tub leaks through the floor to the ceiling and the downstairs goes through the floor to the basement. Not alot of water but enough to cause damage. It doesn’t happen when we us the shower. It seems to be related to the pull of the water draining. Our house is old (1909) but the plumbing was updated around the 80’s. Can anyone help before we decide to go broke replacing all the plumbing?!