How relining works
A plumber will first clean the pipe back to its walls, cutting out roots and jetting away build-up. Next, a flexible liner soaked in resin is fed in, pressed against the old pipe and left to cure hard.
What's left is a new pipe, with no joints along the lined length, sitting inside the old one. Branch connections are reopened from inside with a cutting tool, and the camera goes through again to show the finished line.
Signs relining may suit your drain
- Roots keep coming back in the same spot after clearing.
- A camera shows cracks or open joints, but the pipe still holds its shape.
- The damaged run sits under a driveway, slab, deck or established tree.
- Digging would mean lifting paving or landscaping you want to keep.
- Cracks are spread along the run rather than at one broken spot.
Relining or digging up
| Relining | Dig and replace | |
|---|---|---|
| Digging | Little or none: the work goes in through access points | A trench along the damaged section |
| Needs first | A clean pipe and a camera inspection | A clear path to dig, with other services marked |
| Suits | Cracks, open joints and root entry in a pipe that keeps its shape | Pipes that have collapsed, or dip badly enough to hold waste |
| Branch lines | Reopened from inside after the liner cures | Reconnected in the open trench |
| Afterwards | Footage of the lined pipe | Ground, paving or garden to put back |
When relining isn't the answer
A liner needs something to line. If the old pipe has collapsed, a section has dropped badly, or the camera can't get through, a plumber will usually dig and replace that part, and may reline the rest.
Some jobs need both: a short trench where the pipe has failed, and a liner either side of it. Our guide compares relining and replacement in more detail.
What changes the job
- Length and pipe size: a longer run, or a pipe that changes size partway, means more liner and more set-up.
- Bends and branches: each junction has to be reopened from inside, and tight bends are harder to line.
- Access: relining works from an inspection opening or a small access pit, and if neither is close, one has to be made.
- Condition: heavy roots or thick scale add cleaning time before any liner goes in.
Is it your pipe to reline?
Before paying to reline a pipe near the street, find out whether it's yours. Which part of the sewer belongs to you depends on the water company, and our guide on who owns the sewer pipe sets out each one.
In Sydney, Sydney Water says it may repair private collapsed wastewater pipes under a public footpath or road for residential customers, and it may also repair sections "deeper than 2.5 metres". If your damage is in either spot, talk to Sydney Water before you book anyone.
Before the plumber comes
You can
- Look out any drainage plan or sewer diagram you were given when you bought.
- Note which trees and paved areas sit over the drain line.
- Clear a path to the inspection openings and the gully.
- Ask for the footage from any earlier drain clearing.
Leave to a licensed plumber
- The camera inspection, and the call between relining and digging.
- Cleaning and root cutting before lining.
- Installing the liner and reopening branch lines.
- Lodging whatever compliance paperwork your state requires.
Rules and paperwork
In NSW, a Notice of Work outlines plumbing and drainage work and goes in "before starting work". At the end, a Certificate of Compliance is lodged, drainage work also needs a Sewer Service Diagram, and you should be given a copy.
In SA, sanitary plumbing and drainage are on the list of work that needs an electronic certificate of compliance, and it must reach the customer within 7 days of finishing.
In Victoria, only licensed plumbers can issue compliance certificates, so check the person signing off holds a licence for the class of work, rather than a registration alone.
Questions to ask the relining plumber
- Can I see the camera footage before and after the liner goes in?
- Which sections will be lined, and is any digging needed?
- How will the branch connections be reopened?
- Who lodges the compliance paperwork, and when will I get a copy?
- What does the warranty cover, and is it in writing?
What we would do
Don't choose between relining and digging from a quote alone. Ask for the camera footage, sit down with it, and get the plumber to point at each crack or root and say how they'd fix it. If the damage is near the street, check with your water company whose pipe it is first, then book a drain specialist who does both relining and excavation, so neither option is the only one on offer.