Pipe Relining or Digging It Up? How to Decide

Why pipes need repair rather than another clean-out

A blocked drain that's been cleared once is usually a blockage. A drain that blocks again and again is usually a damaged pipe. Older clay sewer pipes have joints every metre or so, and as the joints open or crack, tree roots find them and grow in. Cutting the roots clears the blockage, but the joint is still there, so the roots return.

What a camera inspection tells you

Before anyone talks about relining or digging, the pipe should be inspected on camera. The footage shows where the damage is, how long the damaged section is, what kind of damage it is, and whether the pipe is in a state that can be repaired from the inside. Ask to see it. It's the evidence the decision rests on.

How relining works

• The pipe is cleaned back to bare pipe, and roots are cut out.
• A resin-saturated liner is inserted through an existing access point.
• The liner is inflated against the pipe wall and left to cure, forming a new, smooth, jointless pipe inside the old one.
• Junctions are reopened and a final camera run confirms the result.

When relining suits

Relining suits cracked joints, root entry, minor offsets and ageing pipes that are still in shape. It's usually the better choice when the pipe runs under a driveway, slab, tree, pool surround or established garden, because nothing has to be dug up and reinstated. It also suits sites where machinery can't easily get in, such as steep blocks.

When digging is the better option

A pipe that has fully collapsed, or has sunk so it no longer drains, usually needs a section dug out. So does a pipe that has shifted badly out of line. A good plumber will say so, rather than push relining where it won't work.

Who pays if the damage is under public land?

Sydney Water's guidance says responsibility for wastewater pipes depends on where its pipes connect to your property, and the connection point is sometimes under a road or footpath. It also runs a program that can cover repair costs for a collapsed private sewer service under public land, if an independent plumber confirms the collapse. Footage is useful evidence, so ask for it, and check Sydney Water's current terms before work starts. In Lithgow, the sewer network is run by Lithgow City Council, not Sydney Water.

Questions to ask any plumber about relining

• Can I see the camera footage of the damage?
• Is the pipe suitable for lining, and why?
• How much of the pipe will be lined, and what will the access points be?
• What will excavation cost for comparison?
• Will I get a final camera run once the liner is in?

Next steps

See our pipe relining page, our blocked drains service, or get in touch. For typical prices, read our guide to what it costs to unblock a drain, which also covers relining.