plumber says reline the pipe or dig it up, which is better

Relining puts a resin-saturated liner inside the existing pipe and cures it in place, forming a new pipe within the old one. It avoids excavation, which is why it is attractive under driveways, established gardens and slabs. It is not universal.

Relining generally works when

• The pipe still holds its shape and its grade.
• The problem is cracking, joint displacement or root intrusion.
• There is access at both ends of the section.

Replacement is needed when

• The pipe has collapsed, so there is nothing to line.
• There is a belly, meaning a low section holding water. A liner follows the existing shape and preserves the fault.
• The grade is wrong, which no liner can correct.
• Too many junctions fall within the section for reinstatement to be practical.

What to ask for

Insist on seeing the camera footage yourself, with the distance counter visible, and ask the plumber to point out the specific defect on screen. A recommendation you have seen the evidence for is a different thing from a recommendation you have been told about, and the good operators offer the footage before you ask.