How To Replace Broken Cast Iron Soil Pipe

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Repair broken sewer pipe easily

Cast iron pipe rots. It will take a long time, but, eventually, cast iron pipe, the old bell and spigot type, will deteriorate to the point that it becomes punky and soft. You may discover that a section of the old pipe under your house is cracked and leaking. How do you remove and replace it?


Preparation – Choose The Right Tool


  1. The first thing to do is rent a pair of soil pipe cutters. Most rental stores, and even some hardware stores, carry these specialized tools and rent them out to their customers. There are two types of soil pipe cutters. One operates with a ratchet handle. This type works especially well in tight places like crawl spaces and in between stud and joist spaces. You loosen or open up the cutter chain jaws with the knob, place the cutter chain around the soil pipe and engage the chain with the jaws, then tighten the knob. Once you have the chain in place and tight, you operate the ratchet handle until the cutter chain breaks the cast iron soil pipe. These tools require some experience to operate successfully. If you are unfamiliar with this tool, ask someone at the rental yard or hardware store to demonstrate it for you.


  1. The second type is a large soil pipe cutter that looks somewhat like a pair of pliers with a cutter chain attached to the end of pliers. You need quite a bit of space to operate these cutters. They work great outside and in ditches. Once again, you loosen or open up the jaws with an adjustment handle near the jaws of the unit, place the cutter chain around the soil pipe where you want to cut it, tighten the adjustment handle which should open the handles of the soil pipe cutter far apart. Resting one handle on the ground or against yourself, press the other handle together toward the first one like closing a pair of pliers. If you have adjusted the soil pipe cutter properly the cast iron soil pipe will break cleanly.


The Problem


  1. The problem comes in trying to cut that old deteriorated cast iron soil pipe. You have to keep cutting away at it until you find a section of the pipe that is solid enough to cut cleanly.


The Repair


Then clean the outside of the pipe well, slide your Fernco or Mission rubber coupling over both ends of the old cast iron pipe, cut a new section of ABS or PVC DWV (drain, waste, and vent) plastic soil pipe to fit and install the couplings.


Tips and Tricks


  1. You can also use no-hub couplings of the proper size to make your connections.


  1. The clamps on the couplings should be tightened with a special torque wrench or to 12-inch pounds. Do not over tighten the clamps or they will strip.


  1. Note that DWV or drain, waste, and vent plastic pipe is the same or nearly the same outside dimension as cast iron soil pipe. But copper DWV pipe is a different outside diameter entirely and cannot be used in this instance.

Cast Iron Soil Pipe

Repair old cast iron soil pipe with the right tools and techniques.
Repair old cast iron soil pipe with the right tools and techniques.

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Comments 15 comments

Unknown 7 years ago

Very Helpful...Sincerely Thanks!

Roger 7 years ago

Very valuable. I would have missed the cutter and made a second trip to the rental store.

Jerry 7 years ago

Thanks, Roger. I'm glad to be of help.

elf_cash profile image

elf_cash 7 years ago

Nice job Jerry, that tips and tricks section is great for beginners, I notice that I've had to "fix" home do-it-your-selfers work quite often and if they had a resource like this I'm sure there would be far fewer problems. Again, good hub!

Mike D 6 years ago

What would be a "rough cost estimate" for a plumber to replace a cast iron soil pipe from 1st floor bathroom toilet to drain in basement concrete with new pvc?

bonnie 6 years ago

hi i am wondering ..the pipe is rotted to the elbow..and we need to save the elbow. how do we salvage as much of it as possible?

Crimping Tools 6 years ago

Thanks for your sharing my friend

It is very helpful for my work

Cast Iron Soil Pipe 6 years ago

Repairing Cast Iron Soil Pipes can be expensive, and hard to source. Cast waste pipes are more expensive to purchase but will out last plastic. Excellent blog!!!

Cable Tie Tools 6 years ago

Thanks my friend ,It is very helpful for work

But I think that It will cost lots of money and time to do

Pipe Cutters 6 years ago

Very helpful

Thanks so much

Jerry 6 years ago

You're welcome! Thanks for reading. Have a great day.

JD 6 years ago

Another option on cutting the cast iron is using the "torch" diamond blade made by Milwaukee in any reciproacting saw. It worked very well in removing 2" cast iron in a tight space in a wall for me, but it takes a few mintues to get through the material and gets hot. They make a longer blade for 4" pipe.

Jerry Watson profile image

Jerry Watson 6 years ago from Hermitage, Tennessee Author

Yep, I've heard of them but they came out after I retired, I think. Great resource info. Thanks for your contribution.

all the best,


whitton profile image

whitton 5 years ago

Nice Hub. These are some great tips Jerry.

speedfit 5 years ago

Thanks for this post! This is all a nice tip to get an easier work regarding this pipes.

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