A drain pipe usually breaks because deterioration, ground movement, external loads, root intrusion or poor installation weakens it. Several factors may combine. For example, roots may enter an ageing joint before soil movement causes it to separate.
Common causes
- Ageing and corrosion: Pipe walls, seals and joints can become brittle, thin or weak. Metal pipes may corrode until they crack, perforate or collapse.
- Tree root intrusion: Roots usually enter through an existing gap, leaking joint or crack. As they grow, they can widen the defect and displace already weakened joints.
- Ground movement and soil pressure: Settlement, erosion, reactive soil or nearby excavation can remove support, crack rigid pipes, separate joints or deform inadequately supported sections.
- External loads: Vehicles, construction activity and insufficient soil cover can crush or deform buried drains. The risk depends on the pipe’s material, depth, bedding and support.
- Installation defects: Poor bedding, inadequate support or misaligned joints can concentrate stress and allow settlement. Incorrect fall may also encourage recurring buildup that contributes to drain pipe damage.
- Severe blockages: A persistent obstruction may add stress to a deteriorated or displaced pipe, but an ordinary blockage is unlikely to rupture an otherwise sound gravity drain.
- Material defects: Less commonly, a defective pipe or fitting creates a weak point that later fails under corrosion, movement or loading.
Why inspection is needed
The fracture alone may not reveal the original cause. A plumber assesses the pipe’s material, age, alignment, location and fracture pattern. Understanding what a CCTV drain inspection can and cannot show helps set realistic expectations: footage can reveal internal cracks, displaced joints, deformation and root growth, but not every external soil load or bedding defect. Controlled excavation may be needed to confirm external damage or loss of support.
Roots inside a drain confirm an entry point but do not necessarily mean the roots caused the initial defect.
What happens next?
- Protect people and the property: Stop using affected fixtures if wastewater is backing up, keep people and pets away, and follow the safe steps when sewage backs up into a house. Do not remove access covers or handle wastewater.
- Locate and assess the defect: The plumber may clear enough obstruction to inspect the line, record the damaged section and locate it from the surface. Severe collapse can prevent the camera reaching the full pipe.
- Select the repair method: A localised defect may be repairable by replacing a section. Relining is only an option where the remaining pipe can support the system, so the inspection must confirm whether pipe relining is suitable for the damaged section. A collapsed, badly displaced, crushed or poorly supported drain may require excavation, replacement and corrected bedding.
- Confirm the quote and responsibility: There is no reliable fixed price before the fault, ownership boundary and access are confirmed. The quote depends on the cause, damaged length, location, depth, access, repair method, materials, labour, current market conditions and any further defects found.
- Test and document the repair: The plumber should confirm flow, inspect the completed work where appropriate and explain any maintenance, warranty or approval records.
Avoid contact with sewage. Do not excavate near buried services or attempt drainage repairs yourself. For recurring blockages or a suspected break, contact our CCTV drain inspection team to locate the fault and recommend a suitable licensed repair.