Leaky drain in the bathtub, water downstairs.?

Good luck to you. You can try it without accsessing the bottom.

Be careful when you use the tub tool. Sometimes the old drain piece will snap at the 'cross hairs'. If that happens, you will have to pretty much replace the whole Waste and Overflow kit. That means you will need access to behind the tub and underneath. I would also recommend that if you unscrew it successfully, don't take it all the way out. After you get it up far enough to apply the putty, do it. Use a ton of it, fix it the first time. Don't use the tool that looks like a tuning fork. it or the the drain will break. They make a tool that looks like a solid piece of metal that will fit down in the drain and fit securely so you can turn it out a-lot smoother. And I believe there is such a thing as inside pipe wrenches that I have heard good things about.

The drain el has a rubber washer between the flange and the bottom of the tub. Putty is used only between the drain insert and the porcelain of the tub. Use a slip-joint pliers inserted into the drain insert to tighten it.

Unless you get lucky, you will need to get under the tub to fix this problem. The leak is out of the tub, on the underside. When these are installed, plumbers putty if put on both sides and a nut on the bottom was tightened.