When an underground drain is cracked, leaking or repeatedly blocked, homeowners generally have two main repair options: pipe relining or traditional pipe replacement.
In many cases, pipe relining in Nowra is the less disruptive solution because damaged sections can be repaired without excavating the entire drainage line. However, replacement is still necessary when a pipe has completely collapsed, shifted significantly or has an incorrect gradient.
The right option depends on the condition of the existing pipe, its location and the cause of the drainage problem.
What Is Pipe Relining?
Pipe relining is a trenchless drain repair method that creates a new pipe within the existing damaged pipe.
Often referred to as cured-in-place pipe (CIPP) technology, the process involves installing a resin-saturated felt or fibreglass liner inside the existing drain. The liner is positioned against the pipe wall and cured, forming a strong, seamless internal layer.
Before installing the liner, plumbers will generally use a CCTV drain camera inspection to identify cracks, tree root intrusion, offset joints, corrosion or other structural defects.
The drain may then be cleaned using hydro jetting or root-cutting equipment before the liner is installed.
Because excavation is kept to a minimum, pipe relining can be particularly useful where drains run beneath driveways, concrete slabs, paving, established gardens or other areas that would be expensive to remove and reinstate.
When Is Pipe Relining the Better Option?
Relining is commonly considered when the original pipe still has enough structural integrity to support a new internal liner.
It can be suitable for:
- cracked or fractured drainage pipes
- leaking pipe joints
- tree root intrusion
- corrosion and deterioration
- minor joint displacement
- pipes underneath concrete or landscaping
- difficult-to-access sewer or stormwater lines
Older vitrified clay and earthenware drains are particularly vulnerable to root intrusion because roots can enter through deteriorated joints and fractures.
Once the roots have been removed, a joint-free liner can seal the damaged areas and reduce the likelihood of roots re-entering through the same defects.
When Is Pipe Replacement Necessary?
Pipe relining cannot solve every drainage problem.
A completely collapsed pipe may need to be excavated because there is no longer a suitable host pipe through which a liner can be installed.
Replacement may also be required where CCTV inspection identifies:
- severe pipe displacement
- major deformation
- missing pipe sections
- significant backfall
- an incorrect drainage gradient
- a large pipe belly holding wastewater
Relining generally follows the existing shape and alignment of the drain. This means it cannot correct a pipe that has been installed with insufficient fall or has moved significantly due to soil movement.
In these situations, excavation allows the damaged drainage to be removed and new PVC or other approved pipework to be installed at the correct level and gradient.
Which Option Costs Less?
The cheapest option depends heavily on where the damaged pipe is located.
If a short section of pipe is only a few hundred millimetres beneath an open lawn, excavation and replacement may be relatively straightforward.
However, the cost of replacement can increase significantly when the drain is beneath concrete, paving, landscaping or structures.
The total replacement cost may include concrete cutting, excavation, machinery, spoil disposal, new pipework and reinstatement of the surrounding property.
Relining can have a higher specialist installation cost, but it may avoid many of these secondary expenses.
For this reason, homeowners should compare the total project cost, rather than relying only on a price per linear metre.
How Is the Best Repair Method Determined?
A professional assessment should start with a CCTV drain inspection.
The footage allows the plumber to determine whether the pipe can support a CIPP liner or whether excavation is required.
Drain locating equipment may also be used to identify the exact position and depth of the defect.
Factors including pipe material, diameter, access, tree roots, structural damage, gradient and surrounding property conditions should all be considered before recommending a repair.
Pipe Relining or Replacement: Which Is Better?
For a structurally damaged pipe that is still reasonably aligned, pipe relining is often the preferred option because it can provide a long-term repair with significantly less excavation and property disruption.
Traditional pipe replacement remains the better choice when the existing drain has collapsed, has severe movement or needs its gradient corrected.
Neither method is automatically right for every property.
The most reliable approach is to diagnose the drain using CCTV equipment and choose the repair method based on the actual condition of the pipe rather than simply selecting the least expensive option upfront.
In NSW, drainage repairs should also be completed by appropriately licensed professionals and in accordance with applicable plumbing and drainage requirements, including the Plumbing Code of Australia and relevant AS/NZS 3500 standards.