Tree roots damaging pipes or foundations: who is liable?

What tree roots actually damage

Roots don't usually break sound pipes for fun: they follow moisture and oxygen. A tiny leak or an old joint in a clay or earthenware drain draws fine roots in, and once inside they thicken and block the line. The most common problems homeowners bring us are:

• Blocked or cracked drains and sewer pipes (recurring blockages, gurgling, slow drainage).
• Lifted paths, driveways and paving where surface roots have thickened.
• Cracked slabs, footings and walls, especially on reactive clay soils where a thirsty tree dries out and shrinks the ground.
• Lifted or cracked retaining walls and pool shells.

The cause matters, because liability follows damage that a tree owner is legally responsible for, not the mere presence of roots.

The starting point: you fix your own land

As a general rule, each owner is responsible for their own property, and you own the tree that grows on your land along with the duty to manage it. If your own tree's roots crack your own slab, that's your cost. It gets more complicated when the tree belongs to a neighbour or the council and its roots cross the boundary and cause damage on your side.

Your right to cut roots at the boundary

You have a common-law right of abatement: you may cut back roots (and overhanging branches) to the boundary line, at your own cost, without asking your neighbour, provided you stay on your own land. Two important limits apply:

• You must not cut so aggressively that you kill or destabilise the tree. Sever the wrong structural roots and you can be liable if the tree later fails, so heavy root pruning is a job for a qualified arborist, not a mattock.
• If the tree is protected by a council tree order or overlay, cutting significant roots can need approval just like removing the tree would. Check the permit checker for your address before you start.

Abatement lets you stop the encroachment. It does not, by itself, get your repair bill paid by the neighbour: that is a separate question.

When the tree owner can be made to pay

Recovering the cost of damage from a neighbour usually depends on showing the encroaching roots amount to a nuisance or that the owner was negligent. The path depends on your state:

• NSW. The Trees (Disputes Between Neighbours) Act 2006 lets you apply to the Land and Environment Court, which can order a neighbour to prune or remove a tree, carry out works, or pay compensation where the tree has caused, or is likely to cause, damage to your property.
• Queensland. The Neighbourhood Disputes (Dividing Fences and Trees) Act 2011 makes the tree-keeper responsible for the tree, and QCAT can order works or compensation where roots cause serious damage or are likely to.
• Other states and territories. There is no equivalent tree-specific tribunal, so claims generally rely on common-law nuisance and negligence, often started as a civil claim. Give the tree owner written notice of the problem and a chance to fix it: an ignored warning is what turns a natural event into negligence.

In every case, evidence is what wins: a plumber's CCTV drain report identifying the roots, an arborist's opinion linking them to the tree, dated photos, and copies of any warnings you gave in writing. Our guide to who pays for tree removal covers the wider liability picture.

Council and street-tree roots

If the roots come from a council street or park tree, the council is the tree owner. Report the damage in writing with photos and any plumber's report. Be realistic, though: many councils have policies that limit their liability for gradual root damage, and outcomes differ between councils. You will almost always need solid evidence that the damage came from the council tree before a claim is considered. Never cut or remove a council tree yourself, as that can be an offence in its own right.

Where insurance fits (and often doesn't)

This is where people get caught out. Many Australian home-and-contents policies exclude damage caused by tree or plant roots, and separately exclude gradual damage that builds up over time rather than a sudden, one-off event. Root damage to underground pipes and drains is a common named exclusion. Cover varies widely, so:

• Read the product disclosure statement and search it for “roots” and “gradual”.
• Call your insurer before you assume a claim will be paid, and before you book repairs.
• Keep the plumber's report: even where cover is limited, it is what any negligence claim against a neighbour or council will rely on.

Before you remove the tree

Taking the tree out stops new root growth, but it will not repair a cracked pipe or lifted path, and dead roots keep decaying and settling for years. On reactive clay soils, removing a large established tree can let the ground reabsorb moisture and heave, cracking slabs the tree was never blamed for. Get an arborist's advice, and an engineer's where a slab or footing is involved, before you commit. Root-barrier installation, drain relining or selective pruning is sometimes a better fix than removal.

Quick reference

• Roots crossing your boundary: you can cut them back to the line at your cost, without killing the tree.
• Your own tree, your own damage: your cost.
• Neighbour's roots causing damage: claim depends on nuisance or negligence (NSW LEC, QLD QCAT, elsewhere common law).
• Council tree: report it with evidence; liability for gradual damage is often limited.
• Insurance: root and gradual damage are frequently excluded, so check your PDS.