Plastic Sewer Pipe To Cast Iron Bell

Question

We are renovating an old house that has a septic system. The pipe to the septic is cast iron. How can we change this pipe to plastic pipe?

Answer

Actually, this is not a big problem. The cast iron pipe hub should be either cut off with a reciprocating saw with steel blade or by renting a large cutter for cast iron, if you have the room. I have done this a few times using the recip saw. Just a warning - cast iron pipe is very hard, but also very brittle. It can be broken with a hammer. Once the pipe is cut off a "mission" fitting, a rubber fitting that slips over the pipe and fastened to the pipe with stainless steel clamps, is used between the cast and the ABS or PVC. Here is a pic of one:

These fittings are the heavy duty rubber with s/s clamps not to be confused with the mj - mechanical joint couplings, which are much lighter and not approved for burial. They may need rubber bushings to match different sizes of pipe, such as 4" cast to ABS, or 4" cast to PVC.

These fittings are generically called Mission, but Fernco is also a brand in my area. Your retailer will know which one you need and the size of bushing if needed, too.

Dave