Pipe Relining vs Replacement: How to Decide Which Is Right for Your Drain

Updated May 2026 — Around The Clock Plumbing Pty Ltd, Oakleigh South.

When a drain has been cleared multiple times and keeps failing, there's a decision to make: keep clearing it, reline it, or replace it. That decision isn't always obvious — and the wrong call costs money. This guide explains how to think through reline versus replace, what CIPP pipe relining can and can't fix, and when excavation and replacement is genuinely the better answer.

What Is CIPP Pipe Relining?

CIPP (Cured-In-Place Pipe) relining installs a structural liner inside an existing pipe without excavation. A flexible liner saturated with resin is pulled or inverted into the damaged pipe, expanded to conform to the pipe wall, and cured — either by heat, UV light or ambient temperature depending on the system used. The result is a new pipe wall formed inside the old one, sealing cracks, closing root entry points, and restoring structural integrity. Our relining work carries a 35-year structural warranty.

When Pipe Relining Is the Right Choice

Relining is the right answer when the pipe has the right failure profile — damage that a liner can seal — and when the alternative (excavation) involves significant disruption or cost. The conditions that suit relining well:

• Cracked or fractured pipe — CIPP seals cracks and bridging fractures, restoring the pipe wall without removing the pipe.

• Root entry points — relining closes the joints and cracks roots are entering through, permanently eliminating the entry point without cutting the roots back repeatedly.

• Pipe under concrete, paving, driveways or structures — where excavation would mean breaking up expensive or complex surfaces, relining eliminates that cost entirely.

• Older clay or concrete pipes that are deteriorating but not fully failed — relining extends service life by decades from the inside.

When Excavation and Replacement Is the Better Answer

Relining has limitations, and a plumber recommending it for every situation isn't giving honest advice. The conditions where excavation and replacement is genuinely the right call:

• Complete pipe collapse — a fully collapsed section has no internal geometry left to support a liner. Excavation and replacement of that section is required.

• Significant pipe offset or belly — a severe joint offset or a section where the pipe has dropped and holds pooled water may not be correctable with relining alone.

• Wrong pipe diameter — extremely small-diameter pipes or those with significant deformation may not allow liner insertion.

• Where the pipe run is short and accessible — in cases where excavation is straightforward and the pipe is in open ground, the cost difference may not justify relining.

The Right Process: Camera First, Decision Second

The reline vs replace decision cannot be made without CCTV camera footage. The footage shows pipe material, crack type and extent, collapse depth, joint condition, and whether a liner can physically be inserted. Without that footage, any recommendation is a guess. Our process: fast arrival → accurate diagnosis via CCTV camera → honest recommendation for the permanent fix that fits the actual pipe condition, with fixed-price quotes for both options where applicable.

A Real Example: 65m Reline Under a Carpark in Carnegie

One of our flagship relining jobs involved a 65-metre drain run beneath a commercial carpark in Carnegie. Excavating 65 metres of carpark would have meant weeks of disruption and significant reinstatement cost. CCTV confirmed the pipe was cracked and had multiple root entry points but retained sufficient structural integrity for a liner. We completed the reline without a single core drill into the surface. The carpark remained in use throughout. This is exactly the scenario relining exists for — a permanent structural fix where excavation would have been disproportionately disruptive and expensive.

Common Questions: Pipe Relining vs Replacement

How long does pipe relining last?

CIPP pipe relining carries a 35-year structural warranty. The liner is chemically resistant and does not provide the entry points for root intrusion that older clay and concrete pipe joints do.

Is pipe relining always cheaper than replacement?

Not always. For short, accessible pipe runs in open ground, excavation and replacement may be comparable in cost. Where relining delivers the biggest cost advantage is under concrete, driveways, landscaping or structures — where excavation reinstatement cost is significant.

Can any pipe be relined?

No. Completely collapsed sections, severely offset joints, and some very small-diameter pipes cannot be relined. A CCTV inspection confirms suitability before any relining is quoted or started.

Will pipe relining reduce the internal diameter of my pipe?

Slightly — a liner adds a few millimetres to the pipe wall. In practice this has no meaningful effect on flow capacity in residential or light commercial drain sizes, and the smoother internal surface of the cured liner often improves flow compared to the deteriorated original pipe wall.

Written and reviewed by Christopher Unwin — founder, Around The Clock Plumbing Pty Ltd, Oakleigh South. BPC Licence #50694, Type A gas, 22 years' experience. National Council member, Master Plumbers Australia & New Zealand.