I have a fiberglass shower stall over 30 years old and it appears that water is going between the black plastic shower drain and the floor of the stall then dripping down the outside of a 4 inch plastic drain pipe underneath the shower. The 4 inch pvc drain fits right up to the bottom of the shower drain so it looks like even if the old drain was full of holes, it would still go into the 4 inch drain and not leak on floor below. I used caulk several years ago to solve the same problem but this time caulk is not doing the trick. I used 100% silicone caulk and went all around the edge of the drain and thought there could be no way for water to seep underneath but it still leaked; thus I assume the only fix is to replace the drain. I read that a wingtite replacement drain might do the trick. What do you recommend?

If you can unscrew the drain lip why not simply take a small ring of plumbers putty and redo the drain seal? Does the shower floor give a bit when you step into it? Regards, Tom

I don't think this is something that unscrews as it is plastic and nothing on it that would assist in turning it right or left; it is most likely glued down. Yes it does give when you step on the floor and allows the floor to sink some so that the water can seep between the drain.

I just read an answer given to similar problem where it was recommended to use pvc primer and then silicone caulk to try to seal the drain and stop the leak. I would be willing to try that but is there something I can do to insure that the problem is not something inside the drain like a hairline crack that might be allowing water to go through? I am worried about trying a repair that don't work and then having to still remove the plastic drain after gluing it tighter to the shower bottom.