View Full Version : Cast iron pipe clogged - this is not good

05-15-2011, 01:41 PM
My recent post had a picture of CI pipe under kitchen sink that had rotted through.

Unfortunately, when I cut out the bad section of pipe I found it is 75% full of sludge even where it is pitched properly. Below are pictures.

1) Should I replace as much of the horizontal run of CI assuming it is full of sludge? Or would it be acceptable to try to snake it clean? It goes about 20' before going vertical to below the slab and another 20' to exit the house.

2) What should I do about the run under the slab? Is it likely to be equally clogged?




05-15-2011, 03:23 PM
As long as the structure of the pipe is sound then cabling and flushing the line should be fine.

You may consider a water jet, to clear it as well.
I would cable it several times without a cutter, and then add the cutter.
Cable onece dry and then with water running through the fixtures when cabling to wash the gunk down stream.

05-15-2011, 03:46 PM
As long as the structure of the pipe is sound then cabling and flushing the line should be fine.

OK. Do I test the structure of the pipe by tapping on it?

05-15-2011, 04:59 PM
First is a visual inspection, can you see any damage or evidence of leakage??

Then go ahead and tap it with a small hammer or the handle of a screwdriver to see if anything crumbles from that effort.
Next would be cabling which will do a final test of the piping.

Sac City Plumbing

05-15-2011, 06:23 PM
When you tap it the pipe should have a ring to it vs a dull thud for a bad pipe.

05-16-2011, 08:06 AM
I decided to go ahead a replace all the cast iron pipe to the utility sink where a plumber had previously installed a PVC Y for a W&D hookup. Partly so I could install a good cleanout for snaking under the slab easily. It's in a crawlspace so I'm not so concerned about sound.

The sludge in the pipe was not as bad as I went further down the line. I think it all goes back to when the house was built in '68 and there was a down bend in the CI where the kitchen fittings connected.

BTW, my Makita battery powered angle grinder with a diamond blade made it easy (but messy) to cut through the pipe.