A displaced drain joint occurs where two adjoining pipe sections have moved out of true alignment, creating a visible step or lateral offset inside the bore. Causes include ground movement, settlement of bedding material, root pressure, and inadequate jointing at original installation. Even small displacements can catch solids, wet wipes and grease, leading to recurring blockages, while larger offsets allow root ingress and ground water infiltration. In older North London streets where Victorian clay drains were laid in short lengths with cement mortar joints, the issue is common. Engineers usually identify displacement during a CCTV drain survey, grading the defect against the WRc Manual of Sewer Condition Classification. Repair options range from patch lining and short liners through to full length cured-in-place lining or open cut replacement where the displacement is severe.
Displaced drain joint
Drain joint that has moved out of alignment, creating a step or gap inside the pipe.
