Pipe Relining vs. Full Pipe Replacement: How to Decide

When an old pipe is cracked, corroded, or has tree roots growing into it, there are two ways to fix it properly: dig it up and replace it, or reline it from the inside without digging at all. Which one makes sense depends on a few specific things about the pipe itself — here’s how to think about it.

What Is Pipe Relining?

Pipe relining creates a new pipe inside the old one. A flexible liner coated in resin is fed through the existing pipe, then inflated and cured in place, forming a smooth, jointless pipe within the original. The old pipe stays exactly where it is — under the slab, under the driveway, wherever it runs — and becomes the structural shell for the new one.

It’s mostly used on sewer and drain lines rather than pressurised water supply pipes, since it works best on pipes that are still structurally intact enough to hold a liner, just damaged or corroded on the inside.

What Full Pipe Replacement Involves

Traditional replacement means excavating along the pipe’s route — through a garden bed, under paving, sometimes under a slab — removing the old section, and installing new pipe before backfilling and reinstating whatever was on top. It’s more disruptive, but it’s the only option when the pipe itself has collapsed, shifted, or is too damaged to hold a liner.

When Relining Makes Sense

• The pipe runs under something expensive to dig up — a driveway, patio, established garden, or the slab itself. Relining avoids all of that.
• The damage is corrosion, cracking, or root intrusion rather than a full collapse — relining needs a pipe that’s still roughly in its original shape.
• You want less disruption and a faster job — relining is typically done in a day or two, without the mess of excavation or the wait for backfilled ground to settle.

When Replacement Is the Better (or Only) Option

• The pipe has collapsed or is badly offset — a liner needs something to bond to; a collapsed section won’t hold one.
• The pipe diameter has been significantly reduced by scale or root mass — beyond a certain point, clearing it enough for a liner isn’t practical.
• The pipe is shallow and easily accessed — if it’s a straightforward dig with nothing valuable on top, replacement is often the more cost-effective route rather than paying a premium for a no-dig method that wasn’t needed.

How We Decide Which One to Recommend

Before recommending either option, we run a drain camera inspection to actually see the condition of the pipe from the inside — not guess based on the home’s age or a single visible crack. That footage tells us whether the pipe is a good candidate for relining or whether replacement is the more realistic fix. We’ll show you what we find and explain the reasoning, rather than defaulting to whichever job happens to be more profitable.

Cost Considerations

Relining often costs more per metre of pipe than a simple, easily-accessed dig-and-replace job — but once you factor in reinstating a driveway, paving, or established landscaping after excavation, relining frequently works out cheaper overall, not to mention faster. For a shallow, easily accessed pipe with no obstacles above it, straightforward replacement is often the simpler and more affordable choice. There’s no single right answer — it genuinely depends on what’s above the pipe and what condition it’s actually in.