Older homes often have cast-iron waste pipes, which can last for decades. Over time, cast-iron pipes can rust through, causing holes, leaking joints or crumbling sections. Repairing small holes or leaking joints is a simple DIY project, but if a section of the cast-iron waste pipe needs to be replaced, then you'll need to call a professional, who will cut out the damaged pipe and replace it with a PVC pipe.
Gently tap the lead back into the joint with a cold chisel and hammer. Be careful when you're tapping not to tap too hard, or further damage could occur.
Brush away any rust or corrosion from around the joint with a wire brush and a rag.
Apply cast-iron repair paste to the area with a putty knife until the damaged area is filled. Let the cast-iron repair paste dry to the manufacturer's recommendations before you use the pipe.
Clean the area around the hole with a wire brush and a rag until all the rust is removed.
Mix two-part plumber's epoxy to the manufacturer's instructions. Press the two-part plumber's epoxy over the hole and mould it to the cast-iron pipe.
Let the two-part plumber's epoxy dry to the manufacturer's specifications before you use the pipe.
Do not disturb the cast-iron pipe's support clamps, or the heavy pipe could come crashing down. Waste is toxic; have a professional repair sections of pipe and any large holes.