We need to connect a new PVC or ABS drain to the existing cast-iron vent and drain. What's the recommended technique?

Asked by Diana Peterson
Ware, MA

It is an older home and the drain ties into the town system.



The connection between PVC and cast iron can simply be handled by installing a flexible coupling.

  • These couplings are made from thick wall rubber and attached to the pipes by use of a large hose clamp or large compression ring.
  • One of the leading manufacturers is Fernco. They offer a variety of sizes and configurations and are available at most home centers and plumbing supply retail stores.

It is essential that you properly measure the outside diameter of both PVC and cast iron pipes so you can purchase the correct size and ensure a leak-free fit.

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