Need help identifying weird sized sewer pipe in older house


My house was built in 1954, the waste pipes under the house are cast iron and galvanized steel, as are the fresh water pipes. I have a clog in the main sewer line running out to the street, as well as a leak that I need to address.

I dug up the line outside of the house in order to install a "sanitary tee" as there was no cleanout, and the plumber couldn't get his camera past a nasty clog in the pipe and suggested I install one. After digging up the pipe and cutting a section out of it in order to install a flexible tee, I discovered that the pipe isn't 4" but more like 4.5".

It's a plastic pipe, but it has a weird dimpled pattern on the outside of it, almost like fiberglass mat, but it's just dimpled into the pipe. It's about the same thickness as schedule 80 ABS, but when broken it almost has a flaky layered type of appearance. A family friend who's a plumber said that it's some kind of obsolete pipe they used during WW2 when they couldn't get cast iron pipe, but I cannot find any information on it. I hate to have to dig up the entire line and replace it, but I can't seem to get any fittings or adapters that will work with this pipe, and I do need to replace at least a couple of sections of it.

Only thing I can think of is possibly if I heated it up to soften it, I may be able to fit a section of 4" ABS pipe inside of it, but I'd rather not go the half-ass route. If I have to replace the whole line, so be it, but wondered if anyone had any input. 🙂

Best Answer

It could be Orangeburg (bituminized) pipe, which was used for decades up to the 70s. I'd remove as much as you can, and then use a shielded Fernco adapter (clamping steel and rubber), sized to the outside diameter. Be careful not to crush the old stuff.

Disclaimer: I have no idea if this meets code.