Tree roots grow into the house sewage drainage pipe some 6+ feet out of the house. Each year I have a company clean out the roots with a large drill. Replacing the pipe will be expensive. What conditions or symptoms should I take as indications that I need to replace the pipe?
If you have roots in your pipe it needs replacing. The cleaning company is just using you as a yearly revenue source. If there is a leak in your waste pipe you are leaking untreated waste into the ground. Not particularly good from an environmental standpoint.
Have a look into pipe burst. These guys actually pull a new pipe through the old one breaking up the old one as it goes.