Repairs to Cast-Iron Pipe


Old cast-iron drainpipe can behave unpredictably. Sometimes a small section of a pipe starts to crumble or a joint begins to leak even though most of the pipe is sound.

If a cast-iron pipe is failing at several points, the most economical solution is to replace it with PVC pipe. This is a job for a professional.

Older cast-iron joints were sealed with molten lead, but this is not a danger to your health because only wastewater passes through the pipes.

Safety First
Support cast-iron pipe

Cast-iron pipe is very heavy and must be held in place with special clamps attached to framing members. Never disturb these clamps; if one weakens, a long section of pipe could come crashing down.


An hour to clean and patch a joint; less time to patch a hole

Wire brush, hammer, cold chisel, putty knife

Cleaning metal, applying putty

Make sure that the pipe is well supported

Repair paste or plumber's epoxy

Step 1

If water or a bad smell comes 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 the corrosion.

Step 2

Fill the resulting void with cast-iron pipe repair paste. Use a putty knife to apply the paste.

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One Hour or Less

Three simple projects to cross off of your to-do list -- just print these instructions and begin!