Replacing Cast Iron With PVC Sewer Pipes


Remodeling a bathroom or kitchen will often require the replacement of old cast-iron sewer or drain lines. Gaining access to the sewer line will be the most difficult part of the project. Cast-iron sewer lines are usually located under the floor in single-story dwellings. If there is a bathroom above the first floor, there may also be sewer lines in the ceilings and walls. Replacing cast iron with PVC sewer pipes is not a job for the amateur. If you have any doubt, consider calling in a professional just for this portion of the remodeling project.

Things You'll Need

  • Cast-iron snap-cutter
  • Measuring tape
  • PVC pipe
  • PVC saw
  • 2 flexible couplings
  • No-hub torque wrench
  • Clean as much of the rust and/or paint off the cast-iron pipe surface as you can. You can use a hammer and chisel, a file or a grinder. The smoother the pipe surface, the better.

  • Cut out the section of cast iron with a cast-iron pipe snap cutter. Alternately, you can use a reciprocating saw with a cast-iron blade.

  • Measure the distance between the cuts and deduct 1/2 inch for expansion.

  • Mark and cut a new piece of PVC pipe with a PVC pipe saw.

  • Remove any imperfections from the ends of the PVC pipe cuts with a PVC deburring tool.

  • Slide a flexible coupling on each end of the new PVC pipe.

  • Center the PVC pipe between the cast iron and slide the couplings halfway onto the cast-iron pipes.

  • Tighten the steel bands of the flexible couplings with a no-hub torque wrench.

  • Turn on all faucets and flush all toilets connected to the sewer line. Run as much water as you can through the sewer line repair to test it for leaks.

Tips & Warnings

  • If you can, block the end of the sewer line with a test ball, then fill the line with water to test for leaks.
  • Cast iron pipe is heavy; a helper might be needed to remove the piece you are cutting out.
  • Follow the manufacturer safety and equipment operating instructions when using a power tool.

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  • Photo Credit Hemera Technologies/ Images
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