At the first sign of trouble that your tub drain is leaking, it is time to take action. If you leave the leak alone, you run the disk of damaging your home. The wood can rot, and mold can grow from the constant moisture. Unfortunately, it usually takes a long time before people notice that there is a problem. Fixing a leaking bathtub drain is so simple that almost anyone can do it.
Remove the drain plug or bathtub stopper. Some drain plugs will simply lift out while others need to be unscrewed from the cross-hair piece.
Unscrew the bathtub drain. Take some channel-lock pliers and insert the handles into the bathtub drain. Fit each handle into the space of the x-shaped cross hairs. Sometimes the cross hairs are missing. If that is the case, then you need a drain key. The drain key internally grips in a 360-degree pattern as it expands against the sides of the drain so you can screw it out. You can find this tool at almost any home improvement center.
Place a screwdriver in the teeth of the channel-lock pliers. Turn the pliers counterclockwise to remove the drain.
Turn on a hairdryer to the heat setting. Aim the hot air at the old plumber's putty until it softens enough to remove.
Clean the old putty away. If the putty has turned hard and crumbly, scrape it away using a plastic putty knife.
Remove a chunk of putty from the container. The putty should be the size of a silver dollar. Roll the plumber's putty between your hands for one to two minutes to soften. Roll the material into a rope about the size of a pencil. Don't worry if you get too much. Simply remove the excess that squishes out from under the tub drain with a putty knife and put it back into the container. You can use this again for another project.
Tighten the drain lip back in place. This will fit over the putty you just applied.
Clean away any excess plumber's putty with a damp rag.
Fill the bathtub with water when you've finished. You need to check to see if the drain is still leaking. If you still have a leak, remove the drain again. Scrape the putty away and reapply it as described in Step 6. Once you have the leak stopped, you can use the drain as usual.