Homes before 1950
Expect cast iron stacks and branches inside the house and clay tile or cast iron in the yard. Galvanized steel may be in small drains and vents. These homes often have pipes at or near the end of their service life.
Homes from the 1950s to early 1970s
Cast iron remained common inside. Outside, clay tile and Orangeburg both appear. Orangeburg is the one to find early because it can fail suddenly.
Homes from the 1970s to 1990s
PVC and ABS plastic took over, with cast iron still used in some places. Sewer laterals are often PVC, but older clay may remain at the connection to the main.
Homes built since
Modern homes use PVC or ABS throughout, with cleanouts at key points. Problems tend to come from installation, such as bellies or poor joints, not from age.
How to know for sure
A camera inspection identifies the material in your own line. Age is only a clue because repairs and additions mix materials.
The year your home was built tells you what to look for, and a camera tells you what you actually have.
