DIY Plumbing Repair Cast-Iron Pipe With PVC

Cast iron is common in older plumbing systems and is fairly durable. However, over time the iron can rust and develop leaks. When this occurs, repairing the problem requires that you cut out the damaged cast-iron pipe and replace it with more modern and durable polyvinyl chloride (PVC) pipe. The process of attaching the two pipe materials is no problem, but cutting out the cast iron requires a heavy-duty saw.

Safety glasses
Reciprocating saw with metal-cutting blade
Wrench
Male PVC adaptor
Pipe dope
String
Scissors
Female PVC adaptor
Tape measure
Straight PVC pipe
Hacksaw
PVC cement
PVC elbows (optional)

Instructions

- 1
  Turn off all of the water to the home by walking outside to the street and looking for a rectangular or oval-shaped cover in the ground. Lift the cover and turn the inner knob counterclockwise. Re-enter the home and turn on a faucet to drain the remaining water out of the pipes. When no more water comes out of the faucet, proceed with the repair.
- 2
  Don safety glasses and install a metal-cutting blade into a reciprocating saw. Trace the damaged cast-iron pipe back to where it joins with another pipe and has a raised coupler. Cut through the iron pipe using the reciprocating saw.
- 3
  Slide the saw down to the other end of the cast-iron pipe where it joins to the pipe. Cut just beside the coupler on that end. While you do this, ask another person to support the iron pipe so that it does not fall. Once you finish both cuts, pull the cast-iron pipe out of the way.
- 4
  Place a wrench around the end of one remaining coupler and turn it counterclockwise with force to detach it. You may need to use two wrenches to get a better grip. Repeat the process on the other end to detach the remaining coupler from that side.
- 5
  Pick up a threaded male PVC adapter and apply a 1/4-inch layer of pipe dope around the threads. Wrap string around the thread from top to bottom and cut the excess off with scissors. Insert the male adaptor over the pipe end that has the threads on the inside of it. Screw the adaptor on until tight, and then turn an additional time with the wrench.
- 6
  Pick up a female PVC adaptor and apply pipe dope around the inner threads. Wrap string around the threads and then screw it into the opposite pipe until tight. Use the wrench to tighten it just as you did with the other adaptor.
- 7
  Measure the distance between the two adaptors with a tape measure. Cut a straight section of PVC pipe to the same length using a hacksaw.
- 8
  Apply PVC cement around the outside ends of the straight pipe and push them into the ends of the adaptors.
- 9
  Turn the water back on to the home at the outside water main.

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