Just like everything else, sewer pipes don't last forever. Pipes are fairly protected under the ground but can still feel the effects of ageing and the surrounding environment.
Keeping the drains healthy by using them for their correct purpose goes a long way to stopping drain damage. (Take a look at what NOT to put down the drain here - Flushable wet wipes block drains ) But issues arising from incorrect or uneven pipe laying, tree or plant roots and ageing can still occur.
Making the decision to repair pipes or replace them was once straightforward as both processes included digging up large sections of land to access the pipe. What you did when you finally got there wasn't too different. With modern trenchless technology techniques, experts can easily fix most pipe problems from a small access hole, including inserting a new pipe lining into the pipe creating a long-lasting barrier (often 50+ years) inside the original.
The following infographic helps to make the pipe repair or replacement dilemma easier to decide on.
Ref - infographic All Plumbing Inc www.allplumbingva.com