Cast iron pipes are very heavy and must be held in place with special clamps and framing members. When doing repair work on a cast iron pipe, it’s important not to disturb these clamps—if one weakens, a long section of pipe could come crashing down. In addition, some older cast iron joints were sealed with molten lead, but this does not pose a danger to your health because only wastewater passes through the pipes. If you need to patch a joint on a cast iron pipe, expect to spend an hour or more doing so. If you’re just patching a hole, it may take even less time.
What You Need
Wire brushHammerCold chiselPutty knifeRepair paste or plumber’s epoxy
Step 1: Clean Away Corrosion
If you spot water or a bad smell coming from an old leaded joint, use a cold chisel and hammer to gently tap the lead back into the joint. Use a wire brush and rag to clean away any corrosion.
Step 2: Fill with Repair Paste
Fill the resulting void with cast iron pipe repair paste, using a putty knife to apply the paste evenly.
Step 3: Fill Any Holes
If a pipe rusts through or is punctured, clean the opening with a wire brush and fill the hole with a two-part plumber’s epoxy. Check the manufacturer’s instructions for drying time, and make sure the pipe isn’t in use until the patch has been completely set.
