There are many ways to repair bathtub drains. Using epoxy putty has to be the easiest and fastest way to repair a lead bath drain under your house. If your lead drain is under the bathroom or kitchen sink, epoxy putty is still the best choice.
Rough the drainpipe surface around the drain leak. Wearing a respirator for safety, sand the area in, on and around the leak with rough grit sandpaper. Sanding will help the putty stick to the lead drainpipe.
Work a small amount of putty with your hands until it is warm and uniform in colour.
Press the putty into the leak of the lead drain line.
Form the putty around the lead pipe. Working quickly, flatten the putty with your hands from the centre of the patch to the outer edges.
Test for leaks. Wait the manufacturer's recommended drying time, turn the water on in the bathtub and check for leaks.
Use rubber gloves to keep your hands clean.
Lead is a health hazard; make sure your respirators rated for lead protection.