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Tree Roots in Sewer Pipe: Symptoms, Causes, and How a Plumber Clears Them
Tree Roots in Sewer Pipe: Symptoms, Causes, and How a Plumber Clears Them, a Prime Plumbing & Gasfitting plain-English guide to tree roots in sewer pipe for Melbourne homeowners. Below we cover what works, what doesn't, and when to call a licensed plumber.
Quick answer: Tree roots find their way into sewer pipes through cracks, ageing joints, or fractured sections, particularly common in older Melbourne homes with old clay (clay) sewer lines. Once inside, the roots feed on the moisture and nutrients in the line and grow into thick mats that catch toilet paper, wipes and waste, causing recurring blockages, slow drainage, and gurgling at fixtures. A plumber clears roots with mechanical cutting (electric eel with root-cutter blade) or high-pressure hydro jetting, then inspects the line with CCTV to find the entry point. Cutting buys you 6-24 months until roots regrow; a permanent fix means excavation and pipe replacement: opening up the affected section and replacing it with PVC. There's no shortcut to a permanent solution where the pipe itself is damaged.
How tree roots get into sewer pipes
Sewer lines are pressurised internally only when they're being used; most of the time they hold air. The pipe walls separate that internal environment from the surrounding soil, and the soil around a sewer pipe is moist, slightly warm, and rich in nutrients because of small condensation and slow seepage.
To a tree root looking for moisture and nitrogen during a dry summer, that's a target. Roots explore in the direction of moisture and nutrients, and once they find a crack, joint gap, or fracture in a sewer line, they grow toward and then into the pipe.
Once inside, they thrive. The sewer line offers everything a root wants: water, nutrients, no competition, and protection from drying out. Roots can grow rapidly inside a pipe, branching into thick mats that fill substantial portions of the cross-section.
This is most common in:
- Old clay (clay) sewer pipes: common in Melbourne homes built before about 1970. The joints in clay lines are sealed with mortar that breaks down over decades.
- Old PVC lines with damaged joints: less common but still happens
- Pipes near established trees: particularly water-seeking species: willows, poplars, eucalypts, plane trees, fig trees
- Lines passing under shifting soil: where settlement has cracked the pipe
Newer (newer) PVC sewer lines installed correctly with rubber-ringed joints are much more resistant to root intrusion, but not immune. Even PVC fails eventually if there's ground movement or an undetected crack.
The symptoms
Root intrusion rarely shows up overnight. It's usually a slow build-up of small symptoms over months before something obvious happens.
Early signs
- Slow drainage at one or more fixtures, basin, shower, toilet
- Gurgling at drains when water is running elsewhere in the house (vent pressure issues caused by a partially-blocked main)
- Rising water level in toilet when nobody's used it (sluggish drain in the line)
- Faint sewerage smell in the bathroom, laundry or yard
Mid-stage signs
- Recurring blockages: toilet or drain blocks, you clear it, and it blocks again within weeks or months
- Multiple drains backing up at once: toilet, shower, basin all slow
- Wet patches in the lawn along the sewer pipe route
- Small sinkholes or settlement above the pipe
Late-stage signs
- Sewerage backup into the bath, shower or floor waste
- Visible damage at ground level above the pipe
- Water bills creeping up if there's also a water-supply leak alongside the sewer damage
If you've cleared a toilet or main drain blockage in the last 6 months and you're starting to see slow drainage again, that's the cycle. Roots regrow after cutting and the blockage rebuilds.
How a plumber finds and clears tree roots
Step 1, Initial clear
The first job is to get the drain working. Two main tools:
Electric eel with root-cutter head: a flexible cable with a rotating cutting blade at the tip, fed down the drain from an inspection point or roof vent. The blade cuts roots and breaks up the blockage. It's fast and effective for clearing the immediate issue.
Hydro jetting: high-pressure water (up to 5,000 psi) sprayed through a directional nozzle that scours the pipe walls, washes out roots, and removes built-up sludge. More thorough than eels and better for clearing the full pipe diameter, especially in larger lines.
For a sewer line packed with roots, we'll usually start with the eel to make a passage, then follow with the jetter to clean it out properly.
Step 2, CCTV inspection
After clearing, we run a CCTV drain camera through the line. The camera shows:
- Where the roots entered (the failure point)
- How much pipe is affected
- Whether the pipe is still structurally sound or is fractured
- Joint condition along the line
- Any other damage (bellies, offsets, collapses)
The CCTV recording is typically saved to a USB and given to you. It's useful for insurance, future plumbers, or your records when selling the property.
Step 3, Decide on next steps
Based on what the CCTV shows, there are typically three paths:
A. Continue regular cutting/jetting: if the pipe is structurally sound but has a chronic root entry point, scheduled clearing every 12-24 months can keep the line running. Cheapest option short-term but doesn't fix the underlying problem.
B. Excavate and replace the damaged section: open up the affected section, replace the cracked clay/PVC with new PVC, backfill. This is the permanent fix where the pipe is damaged. Cost depends on depth, length affected, and surface above (lawn vs concrete vs paving).
C. Replace the whole sewer line: where the entire run is old clay and showing damage in multiple places, it's sometimes more cost-effective to renew the whole sewer line at once. This is significant work, typically thousands of dollars and several days, but fixes everything.
Relining is a no-dig technique that some plumbers use, but it has trade-offs around cost, root re-intrusion at lining ends, and longevity that we don't recommend for residential Melbourne sewer lines. Excavation and replacement is the lasting fix where the pipe itself is damaged.
For drain clearing and CCTV inspection, our blocked drains service covers everything except relining.
How to slow root regrowth between visits
If you've decided on regular maintenance rather than full replacement, a few things slow regrowth:
- Don't pour grease, oils, or food waste down drains: these feed bacteria that produce gases the roots are attracted to
- Schedule jetting before the dry summer: root growth peaks December-March in Melbourne, when trees are most water-stressed
- Watch what you flush: wet wipes catch on root remnants and turn small partial blockages into full ones quickly
- Check the trees: a tree directly above the sewer line is the prime suspect. We don't recommend removing it without consulting an arborist (large established trees have value beyond what they're costing you), but knowing which tree is involved helps planning
Some homeowners use copper sulphate flushed down the toilet to discourage root growth. Effectiveness is mixed and copper sulphate has environmental concerns, we don't recommend it as a routine measure.
Service area
Prime Plumbing & Gasfitting clears tree-root sewer issues across Melbourne's eastern, south-eastern, inner-east and bayside suburbs. See all suburbs we service
Book a sewer inspection or root clear
Call 0475 407 670 or send through the contact form. For recurring blockages, ask for the CCTV inspection so we know what we're dealing with before scheduling repeat clears.
- BPC #103414: Plumbing Industry Commission licensed
- 4.8 stars on Google
- CCTV recording supplied with the inspection
- Fixed-price written quote before any work
When to call a licensed plumber
The Building and Plumbing Commission maintains a plumbing licence search so you can verify any plumber.
Frequently asked questions
You can if the pipe is structurally intact and the entry is at one defined point. Annual jetting is sometimes the most cost-effective path for older homes where full replacement would cost tens of thousands and the maintenance cost is manageable. The CCTV inspection tells us whether that's a viable strategy or whether the pipe is collapsing and needs replacement now.
They can, over time. Roots that grow into a pipe widen the original crack, eventually fracturing the pipe enough that sections collapse. A small entry point at year 1 can be a 50cm length of crushed pipe at year 10. Catching it early matters.
Not necessarily. Tree removal is a major decision (cost, environmental, aesthetic, sometimes regulated by council older rules). Removing the tree doesn't always solve the problem either, root masses already in the pipe will keep growing for years, and other nearby trees may colonise the same access point. Most homeowners deal with the pipe rather than removing the tree. If the tree is small or you were considering removal anyway, that's a different calculation.
A CCTV inspection often shows the entry point, and matching that to the surface tree layout usually identifies the culprit. Common offenders in Melbourne: established eucalypts, willows, poplars, fig trees, and plane trees. Smaller ornamental trees rarely cause sewer-line root intrusion.
Generally no, sewer pipe damage is classed as maintenance and isn't covered by standard home insurance. Sudden damage from an event (a tree falling and crushing the line, vehicle damage to a yard) may be covered. Some insurers offer specific underground services policies that cover sewer/water lines as add-ons. Check your policy.
In some older Melbourne suburbs, properties share sewer lines. Responsibility depends on where the damage is, if it's on your property, generally yours; if it's at the boundary or shared property, neighbours may share cost. Council and the water authority can advise. Strata properties have their own arrangements.
Mostly. Properly installed PVC with rubber-ringed joints, set on a stable bed, in good ground, at adequate depth, and not directly under aggressive root systems lasts 50+ years root-free. The vulnerabilities are: damaged joints (poor install), ground movement (settling, vehicle traffic), nearby aggressive trees, and time. Maintaining good gardens that keep large trees away from the sewer route is the best long-term protection.
How much does sewer root clearing cost?
Indicative ranges only, actual cost depends on access, blockage location, pipe condition, and the path you choose:
- Initial clear with electric eel: typically $350-$650
- Hydro jetting (full line clear): typically $450-$900
- CCTV inspection (with USB recording): typically $300-$500
- Combined service (eel + jet + CCTV): typically $850-$1,500
- Excavation and pipe replacement: highly variable depending on depth, length, surface, typically $3,500-$15,000+ for a residential job
- Annual maintenance jet: typically $400-$700
We always quote in writing before starting.
- When did the issue start?
- Is it isolated to one fixture or multiple areas?
- Are there any visible leaks, smells or unusual sounds?
- Have you turned off the relevant isolation valve?
- Blocked drains Melbourne: emergency drain clearing, electric eel, hydro jet, CCTV
- Burst pipes Melbourne: for water-supply pipe leaks alongside sewer damage
- Emergency plumber Melbourne: for sewer backup emergencies
