Older drains were laid in short pipe lengths with rigid mortar or rubber-ring joints every metre or so. Ground movement pulls these joints apart (open joint) or shifts them vertically (stepped/dropped joint). Each displaced joint is a leak path outward and a root path inward.
Minor displacement is extremely common in old earthenware systems and is a primary target for patching and relining.
A defect term for joint misalignment in jointed pipe runs.
Throughout older earthenware and concrete drains, at roughly one-metre intervals.
A CCTV drain inspection is the standard way to confirm whether this is what's happening in your pipes: the camera shows the condition on screen, a locator pinpoints the exact position and depth, and you get a recorded report before any repair decisions are made.
A CCTV drain inspection shows exactly what's happening inside your pipes — no guesswork.