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Once you've been told your sewer or drain pipe is damaged, the next question is usually the one that matters most: does it need to be dug up, or can it be fixed without tearing up the yard? Pipe relining and pipe replacement solve the same underlying problem, a damaged pipe, but they're very different jobs with different costs, timelines, and levels of disruption.
Neither option is universally "better." The right choice depends entirely on the condition of the pipe, and that's something only a camera inspection can really tell you. This guide breaks down how the two methods differ and what typically decides which one you need.
What's the Difference Between Relining and Replacement?
Pipe relining
repairs the pipe from the inside. A resin-saturated liner is inserted into the existing pipe and cured in place, forming a new, jointless pipe within the old one. It works through existing access points, so there's usually no digging involved.
Pipe replacement
removes the damaged section of pipe entirely and installs a new one in its place. This typically requires excavating a trench along the length of the damaged pipe, which means removing and later restoring paving, garden beds, or whatever sits above it.
Both result in a fully functional pipe. The difference is in how much disruption it takes to get there.
When Pipe Relining Is the Right Choice
Relining is generally suitable when the pipe is structurally intact enough to support a liner. This usually includes:
- Cracked or fractured pipes that haven't fully collapsed
- Pipes damaged by tree root intrusion, where the root has entered through a joint or crack
- Corroded or pitted older pipes, particularly ageing cast iron or clay
- Minor misalignment at pipe joints
- Reduced flow from scale buildup combined with minor structural damage
If a CCTV inspection shows the pipe is intact and roughly in its original shape, relining is often the faster and less disruptive option.
When Pipe Replacement Is Necessary
Replacement is usually the only option when the pipe has failed beyond what a liner can bridge. This includes:
- Fully collapsed sections of pipe
- Pipes that have shifted significantly out of alignment, sometimes from ground movement or nearby construction
- Extensive structural damage along a long section of pipe, rather than a localised crack or break
- Pipes that are too degraded to hold a liner's shape during curing
- Situations where the pipe's diameter or layout needs to change, which relining can't accommodate since it follows the existing pipe's path exactly
In these cases, no amount of internal repair will hold, and excavation becomes the only reliable fix.
How a Plumber Decides Between the Two
The decision isn't guesswork. A licensed plumber will typically:
- Run a CCTV drain camera through the pipe to see the exact location, length, and severity of the damage.
- Assess the pipe's structural integrity, checking whether it's still roughly round and intact or has deformed and collapsed.
- Check for multiple damage points, since scattered damage along a long run may make replacement more practical than relining several separate sections.
- Consider access and depth, as very deep or hard-to-reach pipes can sometimes favour relining purely because excavation would be so disruptive.
This is why an accurate camera inspection matters more than guessing based on symptoms alone. Two pipes with almost identical symptoms, like recurring blockages or a bad smell, can need completely different repairs depending on what's actually happening inside the pipe.
Cost and Disruption Considerations
Relining is generally faster and less disruptive because it avoids excavation and the restoration work that comes with it. Replacement can involve additional costs beyond the plumbing itself, including reinstating paving, driveways, or landscaping that had to be removed to access the pipe.
That said, relining isn't always the cheaper option on a pipe-for-pipe basis, and it isn't suitable for every type of damage. The only reliable way to know which repair, and which cost, applies to your situation is a professional inspection and a written quote.
Get an Accurate Assessment Before Deciding
Choosing between pipe relining and pipe replacement isn't something to decide based on symptoms alone. A cracked pipe and a collapsed pipe can cause identical-looking problems above ground, gurgling drains, recurring blockages, bad smells, while requiring completely different repairs underground.
Coastal Plumbing Professionals can run a CCTV drain inspection to show you exactly what's happening in your pipes and recommend the repair method that actually fits the damage, not just the symptoms.
Contact Coastal Plumbing Professionals today to book a drain camera inspection and get a clear answer on which repair option you need.
Frequently Asked Questions
Can a collapsed pipe be relined?
Generally no. Relining relies on the existing pipe holding its shape to support the liner during curing. A fully collapsed section usually needs to be excavated and replaced.
Is relining always cheaper than replacement?
Not necessarily on a like-for-like basis, but once excavation, paving, and landscaping restoration are factored in, relining is often the more cost-effective option overall for suitable damage.
Can one pipe need both relining and replacement?
Yes. If a long pipe run has one severely collapsed section and other sections with only cracking or root intrusion, a plumber may recommend replacing the collapsed section and relining the rest.
How do I know which one my pipe needs?
A CCTV drain camera inspection is the only reliable way to determine this. It shows the exact condition, location, and severity of the damage.
Does relining work on very old pipes?
Often yes, provided the pipe is still structurally intact. Relining is commonly used on ageing clay and cast iron pipes specifically because it reinforces them without needing to dig them up.
Resources
- Plumbing work | Queensland Building and Construction Commission
- Spotlight on: AS/NZS 3500 Plumbing and Drainage Standards Series – 2025 Updates
