How roots get in
Older clay pipework laid in short lengths has a joint every metre or so, and those joints move as the ground settles. Any gap lets vapour escape, and roots grow towards it. Willow, poplar, birch and any large mature tree within about fifteen metres of a drain run are the usual culprits, though smaller shrubs planted directly over a chamber cause plenty of trouble too.
The signs
- Repeat blockages at the same distance along the run.
- Paper and wipes catching on something that should not be there.
- Slow drainage that returns a few weeks after each clearance.
- Mature trees or heavy shrub planting along the drain line.
- A camera showing fine white or brown root hair inside the pipe.
Removing them
Light root hair is cut back with high-pressure jetting using a root cutting head. Heavier growth, or roots that have hardened over years, needs mechanical drain milling, which cuts the mass back to the pipe wall and leaves a clean bore ready for repair.
Both methods restore flow immediately. Neither is a permanent fix on its own, because the entry point is still open.
Stopping them coming back
The permanent answer is to seal the defect the roots came through. A patch liner across a single entry point, or a full length liner where joints have opened along the run, gives a continuous sealed bore with nothing for a root to enter. That is why we usually recommend cutting and lining together rather than cutting alone.
Where the pipe has been pushed apart or crushed by root growth, the section is excavated and replaced instead.
Do I need to remove the tree?
Usually not. Sealing the pipe is normally enough, and removing a mature tree can cause its own problems with ground movement, quite apart from any conservation area or preservation order. Deal with the pipe first.
Questions we get asked
Will chemical root killers work?
Root foaming products can slow regrowth for a time, but they do not seal the defect and they do not remove an established root mass. They are a stopgap, not a repair.
How quickly do roots grow back after cutting?
In an unsealed pipe, often within a year or two, and faster in a growing season with a large tree nearby. That is why we recommend lining after cutting.
Can roots collapse a drain?
Yes. Over years a root mass can force a joint fully open or crack the pipe, at which point the repair moves from lining to excavation.