Tree removal is generally straightforward, but when roots or machinery strike a buried water pipe, gas line, electrical cable, or drain, the situation can become serious — and expensive — very quickly. Understanding who is responsible, what the legal obligations are, and how to protect yourself before work begins can save you a great deal of stress.
What Underground Services Might Be at Risk?
Most NZ properties have a network of buried services that aren't visible from the surface. These commonly include:
- Water supply pipes (often polyethylene or copper)
- Wastewater and stormwater drains (PVC or older clay/concrete)
- Electrical cables (including mains supply and sub-circuits)
- Gas lines (natural gas or LPG)
- Telecommunications cables (fibre, copper phone lines)
Tree roots are notorious for infiltrating and cracking older clay drains. Equally, excavation equipment used during stump grinding or root removal can easily sever a cable or pipe that isn't marked.
Who Is Responsible for Locating Services Before Work Starts?
In New Zealand, the responsibility for identifying underground services before any excavation is a shared duty — and it's taken seriously.
A reputable arborist should ask you for any service plans you have and, where significant excavation is planned, arrange for a dial-before-you-dig check. The free national service Dial Before You Dig (0800 248 344) connects with utility providers to identify known buried assets. However, it's worth noting that not all private services (such as irrigation lines or older private drains) are registered on these databases, so you should also share any plans you have from your council or original builder.
As the property owner, you have a responsibility to disclose any known services to the arborist before work begins. If you're unsure what's buried on your section, your local council may hold drainage plans, and your lines company can advise on electrical cable locations.
What Happens If Something Gets Damaged?
If an underground service is struck during tree removal, the immediate priority is safety.
- Gas line struck: Evacuate the area immediately, do not use any ignition sources, and call your gas network operator and 111 if there is any smell of gas. Gas work is restricted work and must only be repaired by a licensed gasfitter — find your nearest one through the Plumbers Gasfitters & Drainlayers Board.
- Electrical cable struck: Do not touch the cable or surrounding soil. Call your lines company immediately and keep everyone well clear. Electrical repairs must be carried out by a registered electrician — check credentials at the Electrical Workers Registration Board.
- Water pipe or drain damaged: Turn off the water at the toby (street valve) if possible and contact a licensed plumber or drainlayer. Drain repairs that connect to the public network may require a building consent or at minimum council notification — check with your local council.
Liability: Who Pays?
Liability depends on the circumstances:
| Scenario | Likely Liability |
|---|---|
| Arborist failed to check for services | Arborist (and their insurer) |
| Owner failed to disclose known services | Shared or owner liability |
| Service not on any plan and undetectable | May be shared; insurer decides |
| Owner doing DIY tree removal | Owner bears full responsibility |
A professional arborist should carry public liability insurance — always confirm this before hiring. Ask for a copy of their certificate of currency. If they are a member of the New Zealand Arboricultural Association (NZAA), they are expected to follow a professional code of practice that includes pre-work planning.
If you believe the arborist was negligent, you may be able to make a claim through their insurer or, if unresolved, through the Disputes Tribunal.
How to Prevent Damage Before Work Begins
Prevention is far better than dealing with the aftermath. Here's what to do:
- Get a service location done. Ask your arborist whether they will arrange a dial-before-you-dig check, or do it yourself in advance.
- Obtain your property's drainage plan from your local council — many councils provide these on request or through their online GIS portals.
- Mark known services with spray paint or flags before the arborist arrives.
- Discuss the scope of work in detail. If stump grinding or root excavation is involved, the risk of striking buried services increases significantly.
- Choose a qualified arborist. Look for NZ Certificate in Arboriculture (Level 4) or higher, and NZAA membership. You can find local arborists on tradedirectory.co.nz.
Building Consent and Compliance Considerations
Depending on the extent of damage, repairs to underground services may trigger building consent requirements under the NZ Building Code. For example, significant drain repairs or replacements often require a consent and inspection. Schedule 1 of the Building Act lists some exemptions for minor repairs, but you should always confirm with your local council whether consent is needed before repair work begins — don't assume it's exempt.
BRANZ also provides guidance on building performance and repair standards that may be useful if you're navigating a more complex repair situation.
When to Call a Professional
You should always call a licensed professional if:
- Any gas or electrical service has been damaged (this is legally restricted work)
- A drain connecting to the public network has been broken
- You are unsure of the extent of damage underground
- Your insurer requires a qualified assessment
For tree removal itself, any work involving large trees near structures, power lines, or where significant root excavation is needed should be handled by a qualified arborist. Find a trusted local professional on tradedirectory.co.nz.
ISO 9001 / 45001 / 14001
Tōtika Prequalified
