Reasons to inspect old home:

Many homes were built around 1970s with poor sewer systems,which  disintegrate and collapse over time.

And since these pipes were not made of good material,It is not very difficult for tree roots to grow into these sewer lines.Roots invasion then leads to an accumulation of debris and ends up with backups such as grease or eggshell waste.

Sometimes the cesspools were left intact and connected to the sewer line after the city installed its municipal sewer system.We have to check these kind of problems by run a hand camera down your sewer.