Tree roots damage pipes by finding a weak joint or a hairline crack, growing in through it, then thickening until the pipe blocks or splits apart. It happens slowly, usually over years, and most people don’t notice until a toilet backs up on a Sunday. The fix rarely involves digging anything up. A robotic cutter is fed in through an existing access point, grinds the roots out under camera, and leaves the pipe clear.
We do a lot of this work across Newcastle, Lake Macquarie and the wider Hunter, where plenty of the housing stock still runs on clay or early PVC sewer lines. Here’s what’s going on underground, and what fixing it properly looks like.
Why Roots Go for Your Sewer Line
Roots aren’t hunting for pipes. They’re following moisture.
A sewer line carries warm wastewater, and warm wastewater gives off vapour. Where a joint isn’t perfectly sealed, or where the pipe has a small crack, that vapour escapes into the surrounding soil. To a root, that damp patch is a signal, and it grows straight towards it.
Older clay pipes are the worst for it. They were laid in short lengths with mortar or rubber ring joints, and after 50 or 60 years of soil movement those joints rarely sit as tight as they did on day one. Early PVC holds up better but isn’t immune, particularly where a section has settled or where a lateral has been cut into and patched at some point.
Sandy soils around the lake and the coastal suburbs dry out fast over summer. That pushes roots deeper and wider looking for water, and a slightly leaky sewer line is the most reliable water source in the yard.
How Tree Roots Damage Pipes, Stage by Stage
It isn’t one event. It’s a sequence, and each stage makes the next one easier.
Stage one. A single hair root finds the gap. There’s no symptom at all at this point. A camera would pick it up. Nothing else would.
Stage two. The root thickens inside the pipe and starts branching. Fine root hairs fan out into the flow like a net, and wipes, fat, grit and hair catch on them. Drainage slows a little. You might hear a gurgle from the toilet when the shower empties.
Stage three. The root mass now fills a decent share of the pipe. This is where repeat blockages start. Clearing it buys a few months, then you’re back where you started.
Stage four. This is where the real damage happens. As the root thickens it works like a wedge. Growing wood exerts serious force, and a root the width of your thumb pushing through a clay joint will lever that joint apart or crack the pipe wall around it. That opens a wider entry, which lets in more roots, and soil starts washing in through the gap.
Stage five. The pipe deforms or collapses. Cutting won’t save it now. You’re into replacement or a structural repair, which is a different conversation and a much bigger bill.
Most of the jobs we get called to are sitting at stage three or four. Stage two is the cheap version, and almost nobody catches it there without a camera.
The Trees Most Likely to Cause It
Hunter Water publishes a damage rating list for planting near sewer pipes, and it’s worth a look before you put anything new in the ground. Camphor laurel, figs and rubber plants, poplars and willows are all rated Extreme. Large gums, jacaranda, liquidambar, casuarinas, pines, plane trees and the Illawarra flame tree sit at Very High.
That list covers a lot of what’s already growing in older Newcastle and Lake Macquarie streets. Camphor laurels are everywhere in the Hunter, and they’re relentless.
One thing people get wrong: the tree doesn’t have to be anywhere near the pipe. Roots commonly spread two to three times the height of the tree. A liquidambar four doors up the street can absolutely be the thing sitting in your sewer line.
What You’ll Notice Before the Pipe Fails
The early signs are easy to write off. Together they’re a pattern.
- Sinks, showers or the laundry draining slower than they used to
- Gurgling from a toilet or floor waste when another fixture drains
- A faint sewage smell in the yard, usually strongest after rain
- The same fixture blocking more than once in a year
- A strip of grass over the pipe run that stays greener or damper than the rest of the lawn
The one that matters most is repetition. A single blockage after Christmas is usually something someone flushed. The same blockage twice in twelve months is nearly always roots or a structural fault, and a CCTV inspection will tell you which within about twenty minutes.
Why Clearing a Blockage Isn’t the Same as Fixing It
An electric eel punches a hole through the root mass. Water flows again, the problem looks solved, and everyone goes home happy. But the root is still in there, still attached, and it grows back into the space it just lost. Six to twelve months is typical.
High-pressure jetting does considerably more. It scours the pipe wall and strips soft growth out properly, and for fine root intrusion it’s often all you need. Our standard blocked drain services in Newcastle start there for exactly that reason. What jetting won’t shift is a mature root ball or a woody root that has grown through a joint and set. Chemical root killers won’t either. They burn the tips and leave the structure sitting in the pipe.
That gap is what robotic cutting is for.
How Robotic Cutting Removes Roots Without Digging
It starts with the camera, every time. A CCTV pass tells us where the intrusion is, how far along the run, how much of the pipe it’s taken up, and what condition the pipe wall is in behind it. Guessing at any of that is how people end up paying for the wrong repair.
Then the cutter goes in. It’s a small remotely operated unit with a motorised cutting head, fed through an existing access point such as an inspection shaft or a cleanout. The operator watches the live feed and works the head against the root, grinding it back flush with the pipe wall. It’s slow, deliberate work, and that’s the point. Our robotic cutting equipment handles pipes from 75mm to 300mm in diameter, which covers nearly all residential and light commercial drainage in the region.
After cutting, the camera goes back through. That second pass confirms the pipe is clear and shows the condition of the wall that was hidden behind the roots, which is the part that decides what happens next.
Cutting on its own usually takes two to four hours. Combined with a reline, plan on a day. Either way, nothing in your yard gets dug up.
That last point carries more weight than people expect. If you excavate instead, the plumbing itself might be $3,000. Putting back a concrete driveway, pavers, tiled flooring or established landscaping on top of it regularly costs more than the plumbing did.
When Cutting Needs to Be Followed by Relining
Cutting removes the roots. It doesn’t close the hole they came in through.
If the entry is a slightly displaced joint and the pipe is otherwise sound, cutting on a maintenance cycle can be a reasonable way to manage it, and we’ll say so. But when the camera shows a cracked wall, an open joint or a hole, the roots are coming back. The thing that attracted them, moisture leaking into the soil, hasn’t changed.
Pipe relining is what closes it. A resin saturated liner is installed inside the existing pipe and cured in place, forming a smooth, jointless new pipe within the old one. No joints mean no entry points, and a properly installed liner should give you 50 years.
Cutting must come first because a liner needs a clean, even surface to bond to. Roots, protruding joint lips or hard scale left in place cause bulges and gaps, and the liner won’t cure the way it should. Skip that step and you’ve paid for a reline that fails early.
Who Pays for the Repair
Worth sorting out before you call anyone. Across the Hunter Water area, the property owner is responsible for the sewer pipes and fittings on their property, right up to the point where they connect to Hunter Water’s system. That includes the boundary trap and the inspection shaft.
So, if the roots are in your lateral, it’s your repair, even when the tree doing the damage belongs to the council or the neighbour.
There’s one useful exception. If your inspection shaft is full or overflowing, that points to a blockage in the main rather than on your side, and Hunter Water fixes that one. Call them on 1300 657 000 before you call a plumber in that situation.
Also worth checking your home insurance policy. Some cover damage to underground pipes; plenty exclude anything classed as gradual deterioration. Better to read it now than find out mid job.
Keeping Roots Out Afterwards
A reline is a permanent fix for the section it covers. The rest of the run is still fair game, so a bit of maintenance goes a long way.
- Check the Hunter Water rating list before planting anything within reach of the sewer line, and remember reach means two to three times the mature height
- If there’s already a big tree over the run, book a camera check every two to three years. It costs a fraction of an emergency callout
- Install a root barrier when you plant something new near a known pipe run
- Sort out small leaks and slow drains early rather than waiting for a proper blockage
Get a Camera Down There Before It Backs Up
If your drains are slow, or you’ve cleared the same blockage more than once, get a camera in. It’s the only way to know if you’re dealing with roots, a collapse, or something someone flushed that shouldn’t have been.
Green Planet Plumbing handles CCTV inspection, robotic cutting and pipe relining across Newcastle, Lake Macquarie, Maitland, Cessnock and the Hunter Valley. Call (02) 4911 9402 or request a quote and we’ll take a look.