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Plumbing in the Home/How do I clean the inside of a cast iron pipe?


Hi Dana
The cast iron pipe in my shower(shower only, no tub) is becoming occluded. Water is NOT backing up; I have NO clog at this time; but I removed the drain cover and noticed the buildup; looks like combination of hair & rust. House built in 60-70’s, Tennessee.  I had the cast iron under the house replaced a few years ago with pvc but not the vertical section of cast iron where it enters the flooring. I have tried scraping the sides of pipe with putty knife and long screwdriver(yea, I know, I know...but not as dumb as some of the things I've done), but was not very effective. And since the pipe is vertical, would Zep Draincare even be effective on a vertical section? In other words, would enough of it still cling to the sides of the pipe? I have a snake that attaches to my drill, but again, I do not have a clog; I just want to clean the sludge from the walls of the pipe. Not sure of length…18-24” maybe. Does anyone make an auger-type device or is that likely to break-through the pipe? Been long time since I have been under my house(crawlspace) but seems like there maybe a cleanout on the cast iron(I’m guessing) but never removed in the 22 years I’ve lived here.
Thanks so much.

Hello Don,
Given what you tried already and the age of the pipes the most likely solution is to replace the riser and the trap. If there is that much rust, the pipes are getting pretty thin. Chemicals will not work because they need to sit in contact with the area in question and that's not happening on a vertical pipe.  Chemicals that would attack the rust might also eat away the pipes and cause a leak.

How difficult that would be really depends on how the shower drain is set up. There is a chance that the cast-iron is actually leaded in. That would make it a bit more challenging for a DIY project. I would have a professional plumber, preferably an old timer if you can find one, come in and take a look to see what your options are. It's not that big of a job but it can be challenging as a DIY project.

Good Luck,

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Dana Bostick


Pretty much any residential plumbing questions. For "item specific" details such as a specific model of fixture, I will need to research and there may not be any useful information available. Note: I live and work in Southern California. We do not, as a rule, use hot water or steam heating systems, oil fired boilers or private water wells so my knowledge in those areas is pretty limited. There are others here on AllExerts that can probably answer those questions better.


Retired, Licensed General Contractor with Plumbing license. Active Home Inspector, Litigation Consultant and Infrared Thermographer, Online Marketing specialist.

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