Replacing 3″ Drain

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    • #279320
      Patrick Curran

      I have a couple good-size leaks (1/4in size holes in the bottom of the pipe) in an approx three foot section.
      Coming out down from the kitchen wall, out about a foot, a joint…then the three foot section…then a 90degree turn. All cast iron. The leaks are about three and six inches from the 90 degree turn/joint. So, I have about two feet of good pipe from the first joint as it comes out of the wall. I suspect I should replace the whole section.
      It’s all in a crawl space under which I can work on my
      knees or very bent over. The pipe is fairly close to the floor of the house.
      How do I start?

    • #300536

      Cut out the pipe and fittings where the leaks are and reinstall with plastic pipe and fittings connected by CI-Plastic Fernco connectors. When you refer to “cast iron” drains do you mean hub & spigot or threaded (Durham) iron drain pipe? If the former, you can use a snap cutter to do the cuts, and you can reinstall with CI pipe and regular hubless connectors. If the latter, use a reciprocating saw to make the cuts. Be sure to support the pipes before you cut if there is a chance they will drop.


    • #300537

      Thx for the reply.
      The pipe is not threaded. The house is over 30 yrs old.
      Snap cutter? Can it usually be rented?
      I believe I can rent a saws-all (reciprocating?).
      Not much room between the leaks and the 90degree
      turn for installing a connector…so…somehow disconnect the pipe from the 90 degree joint?
      Sure do appreciate your patience and any info.

      Thx again,


    • #300538

      So the pipe is not threaded…that means it is probably bell & spigot CI with oakum and lead joints. What you need to do then is cut out the offending section of pipe and insert either CI pipe/fittings or plastic pipe and fittings to match the cut out section. You will use either 3″ hubless CI connectors or Fernco CI/Pl connectors. Make sure that your cuts are at least 4″ away from any CI hub.

      The snap cutter is an essential tool. Rigid makes one that works well in tight spaces. It costs over $300. You may be able to rent one. Cutting through CIP is possible with a reciprocating saw and carborundum saw blades. It is slow and hard work, and you will go through 3 or more blades (at a cost of nearly $10 each) just for one cut.

      If you plan to rent or buy the tools for the job, the cost will be a couple of hundred dollars. Unless you plan to use these tools in the future, your best bet would be to hire a plumber and pay him a few hundred dollars to do the job right.


    • #300539

      I finished the job using the Fernco connectors, etc.
      You are WAY correct about the reciprocating saw. I
      went thru 2 blades fairly quickly. Both were designated
      as for cast iron. So, FYI to anyone contemplating this
      job…use the snap cutter.

      Thx again,


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