Responsibility for damaged underground services is rarely simple — it can fall on the earthmover, the homeowner, the principal contractor, or even a combination of all three, depending on how the job was planned and managed. Understanding your obligations before any machine breaks ground is the best way to protect yourself financially and legally.
Why Underground Service Strikes Are Serious
Underground services include water mains, stormwater and sewer pipes, gas lines, telecommunications cables, and high-voltage electrical cables. Striking any of these can cause serious injury or death, significant property damage, and costly repair bills. WorkSafe NZ treats underground service strikes as a significant workplace hazard, and there are clear duties under the Health and Safety at Work Act 2015 to manage this risk before excavation begins.
The Duty to Locate Services Before Digging
In New Zealand, the accepted industry standard is that services must be located before any excavation starts. This is not optional — it is a fundamental part of safe dig planning. The key steps are:
- Contact Before You Dig (CBYD): New Zealand has a free national service (formerly known as Dial Before You Dig) where asset owners register their underground infrastructure. Anyone planning to excavate should submit a request to identify what services may be present.
- Obtain as-built drawings: Local councils and utility companies can supply plans showing the approximate location of services. Note that these are indicative only — actual positions can vary.
- Use a cable and pipe locator: A qualified locating technician or the earthmover themselves (if trained) should physically locate and mark services on the ground before digging.
- Hand dig (pot-hole) near confirmed services: Within the tolerance zone around a marked service, excavation must be done carefully by hand or with vacuum/hydro excavation equipment.
If these steps are skipped or poorly executed, the party responsible for that failure is likely to bear most of the liability.
Who Is Legally Responsible?
Liability depends on the specific circumstances, but here are the general principles:
The Earthmover (Contractor)
If the earthmover failed to check for services, ignored marked locations, or excavated carelessly near known services, they are likely to be held primarily responsible. Professional earthmovers carry public liability insurance specifically for this reason. Always confirm your contractor has current, adequate insurance before work begins.
The Homeowner or Principal
If you hired the earthmover and failed to provide accurate site information, did not arrange a service location, or directed the operator to dig in an area you knew was risky, you may share liability. As the person in control of the site, you have duties under health and safety law. MBIE Building Performance provides guidance on your obligations as a homeowner undertaking building or earthworks projects.
The Asset Owner
In some cases, if a utility company's as-built records were significantly inaccurate and the contractor followed all reasonable steps, the asset owner may share some responsibility. However, this is harder to establish and usually requires legal advice.
Shared or Contributory Liability
Many real-world cases involve shared liability across multiple parties. Courts and insurers look at who had what duty, what steps were taken, and what was reasonably foreseeable.
What Happens When a Service Is Struck?
If an underground service is damaged during excavation:
- Stop work immediately and make the area safe.
- For gas leaks — evacuate the area and call the gas network operator and 111.
- For electrical cables — do not touch anything; call the lines company and 111 if there is danger.
- Notify the relevant asset owner (water, power, gas, telco) as soon as possible.
- Document everything — photographs, notes, and witness details.
- Notify your insurer promptly.
Repair costs for utility infrastructure can run into tens of thousands of dollars, particularly for high-voltage cables or large-diameter water mains.
Contracts and Insurance Matter
Before any earthworks begin, make sure:
- Your earthmover has a written contract that clearly sets out responsibilities for service location.
- They carry current public liability insurance (ask for a certificate of currency).
- You understand what your own home and contents or property insurance covers — some policies exclude damage caused during owner-directed works.
- If a principal contractor is managing the site, confirm in writing who is responsible for the service location process.
Building Consents and Earthworks
Some earthworks require a building consent under the NZ Building Code, particularly where significant cut and fill is involved, or where the work could affect drainage or neighbouring properties. Schedule 1 of the Building Act 2004 lists certain exemptions, but you should always confirm with your local council whether consent is needed for your specific project. MBIE Building Performance has useful guidance on when consents apply.
When to Call a Professional
Always use a qualified, experienced earthmoving contractor for any excavation near existing infrastructure. A reputable operator will have a clear process for service location, will carry appropriate insurance, and will know when to stop and seek further information. You can find qualified local earthmoving contractors on tradedirectory.co.nz. If a service has already been damaged, seek legal advice promptly — liability disputes can become complex quickly.
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