Tree roots are one of the most common causes of recurring blockages and drain damage, particularly on streets with mature trees such as parts of Bassett, Highfield and Upper Shirley in Southampton, and in leafy areas of Winchester and the New Forest.
How roots get in
Roots grow towards moisture and nutrients, and a drain offers both. Fine roots enter through tiny gaps at joints or hairline cracks, which are common in older clay pipes. Once inside, they grow quickly in the warm, wet conditions and form dense mats that catch paper, wipes and grease.
Over time, roots can widen joints, crack the pipe and, in severe cases, cause sections to collapse.
Signs of root ingress
- Blockages that return every few weeks or months in the same drain
- Slow drainage and gurgling from several fittings
- Roots visible in an inspection chamber
- Blockages that get worse in spring and summer, when trees are growing
- Sinking paving or ground near a tree and a drain run
How roots are removed
Roots are usually cut out with specialist cutting heads, either on high-pressure drain jetting equipment or on mechanical cutters. A camera survey before and after shows how extensive the ingress is and confirms the drain is clear.
Why cutting is only half the fix
Cutting removes the roots inside the pipe, but not the gap they came through. Without a repair, they usually grow back, often thicker than before. A CCTV drain survey shows where the roots are entering, so the defect can be repaired. See drain repairs.
What about the tree?
- Removing the tree is rarely necessary and can cause other problems, especially on clay soils where large trees affect ground moisture. Repairing the drain is usually the better answer.
- Protected trees. If the tree has a Tree Preservation Order or is in a conservation area, check with your local council before any work that could harm it, including cutting large roots.
- A neighbour’s tree. If roots from a neighbouring tree have damaged your drain, talk to your neighbour and your home insurer. Keep the survey footage as evidence.
- Shared drains and public sewers. If the roots are in a shared drain or public sewer, the water company is usually responsible. See who is responsible for a shared drain.
Preventing root problems
You cannot stop roots looking for water, but you can reduce the risk by dealing with defects early, avoiding planting trees and large shrubs close to drain runs, and having drains near big trees checked if blockages start to recur.
See also signs of a broken drain pipe.