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Leaking Cast Iron Drain Pipe


I have a cast iron pipe, about 5" diameter, that runs from the second story bathroom and then across the floor between the beams of the first floor, and then down into the sub basement. I have ripped out the plaster/drywall in the celing of the basement room where the best access is. I can see that when there is water comming from upstairs it leaks one drop per 5 seconds or so.

Anyway, this is something I will have to fix myself. I would like to know what experianced people think about the following.

How to cut the bad section out. Can I use a reciprocating saw? There is limited clearace to work with, but I think the sawzall will fit in there.

Also, can this be replaced with PVC? I would think so, but I want to be sure about what I'm doing.

I read and saw on an episode of This Old House where a rubber coupler with hose clamps were used, is this the best way to go? On the show the pipe was replaced with another new piece of cast iron pipe and he used a large expensive chain tool that cut the pipe.

Is there anything else I need to consider to do this job?

Thank you,


Re: Leaking Cast Iron Drain Pipe


Before giving out advice/suggestions about how to replace a section of CI pipe......

Have you for sure determined exactly where the source of this leak is?

If the leak is actually at a joint in the pipe there are simpler means to stop it than cutting out the pipe.

Or.....is the pipe noticably rusted out?

Any chance of a couple pics?

Re: Leaking Cast Iron Drain Pipe

Here's the pictures of the leak. I have it exposed enough that I can be cetain that it is from the cast iron pipe shown. I have the same problem in the sub basement also, but it seems to have sealed itself for now. I just noticed a small pile of very fine brown dirt below where I noticed a simialr looking group of rust.

Re: Leaking Cast Iron Drain Pipe

Water has an incredible ability to trickle and drip far away from the original source so once you're sure where the leak is use a chain cutter to remove the section of cast iron pipe. They are usually available at tool rental places for around $50.00. It will be a snap ( pun ) to use ... 10 minutes you're done.

A reciprocating saw will take a life time to cut through the pipe besides what you will spend on blades will almost be the cost as buying a chain cutter. ;)

Re: Leaking Cast Iron Drain Pipe

The other posters are all accurate with their info.

That pipe is clearly badly cracked & must be removed.

It looks like it's sitting horizontally in the photo.

If it's sitting vertically, make sure you securely brace either side with steel strapping before you make your cut so everything doesn't come crashing down.

Assemble everything that you need before making the cut, as you won't be able to use the drain until you get the new pipe in.

Some towns don't allow cast iron to pvc, but only a very few.

Get the outside diameter of both pipes so you can match it with the new pipe you buy.

The rubber/neophrene boot you mention is a Fernco fitting,available at the big box stores & they come in different sizes.

make sure you get a good fit between plastic & fernco before you leave the store; there are ferncos that have one end slightly larger or smaller than the other to accomodate different pipe materials; pipe supply houses in your area have a wider selection than the big box stores.

The pipe comes in 10' sections, if you only need a few feet, see if they have any remnants for sale.

Use automotive grease/silicone grease or equivalent to more easily slip the fernco on the edges of the pipe.

The old CI pipe can be usually hit with a baby sledge hammer (or even a regular hammer) if it's that far gone; they usually easily break up; use a hammer & chisel at the ends to remove the lead & oakum remnants so you don't damage the end sections.

Wear leather gloves to avoid cutting your hands; there are many bad microbes in these pipes.

Wash your hands thoroughly after the job; if you do get a cut, apply neosporin or bacitracin ointment or equivalent antibiotic ointment.

If the hammer doesn't work, I always use a 7" circular saw if there is enough room, fitted with a metal-cutting blade (brown, emery-looking blade at big box stores for $5); the blade will go right thru the pipe with ease.

This makes a lot of sparks, so make a shield & wear safety glasses, long-sleeved heavy cotton shirt.

Re: Leaking Cast Iron Drain Pipe

Canuk and Jack,

Thank you very much for the details on this job. When I first discover the source of the leak I didn't know what I was going to do. It seemed like it was going to be way too big of a job. I feel confident now that I can do it in a few hours time.

Thanks again.


Re: Leaking Cast Iron Drain Pipe

You will probably have to cut off the hub of the adjoining cast iron pipe, cut the PVC plastic pipe to fit the space. attach the two Fernco fittings and work them onto the existing pipe.

Lubricate the Fernco fittings & shave small amounts off the PVC until you can work the PVC into both ends of the Fernco fittings.

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