Pre-Dig Investigation
Know what’s buried before you break ground
Since 2015Own locators, hydro-vac & diggersAuckland · Franklin · North Waikato
What it is
Before anyone puts a digger or post-hole borer in the ground, we find what is already buried there — power, water, gas, comms and drainage — and mark it on the surface with paint and flags so the crew can dig around it.
When you need it
- You are about to trench, pile, fence or plant on a site with services.
- The utility plans you have are old, vague or contradict each other.
- A contractor will not start until the services have been marked out.
What you get
- Every located service marked on the ground with paint and flags.
- A photo record of the mark-out before it gets scuffed or rained off.
- Depth and position notes, or a GPS map if you need to keep records.
Dig with Confidence with Pre-Dig Underground Service Detection
Before you break ground, it’s crucial to know what lies beneath the surface. Utility Works’ pre-dig investigations give you the confidence to proceed safely by locating power, water, gas, and communications infrastructure.
Servicing Auckland, Franklin, and North Waikato, we work with contractors, developers, project managers, and property managers to ensure every dig is informed and compliant. With Utility Works’ utility detection and mapping, you get accurate data — and peace of mind — before you dig.
What’s included
What a pre-dig investigation covers
Ground Penetrating Radar (GPR)
Where standard methods are not sufficient, GPR scanning provides a detailed image of underground structures and materials.
Learn more about Ground Penetrating Radar (GPR) →Hydro Vac Potholing
A safe, non-destructive digging method to confirm utility locations and depths before excavation.
Learn more about Hydro Vac Potholing →GPS Mapping & Data Reporting
We capture precise locations and deliver survey maps and shapefiles that integrate with your project plans, so you have accurate records for future works.
Learn more about GPS Mapping & Data Reporting →
Don't Dig Blind — Book Your Pre-Dig Investigation Today
Free, no-obligation quote · Mon–Fri 7am–5pm · Auckland, Franklin & North Waikato
Google reviews
What customers say
“Prompt service & fair pricing. Tony and his team — sharp eye for detail and out of the box problem solving paired with a high standard of workmanship.”
Richard La Trobe · Google · October 2026
“Really happy with the work to install our underground services. Highly recommend.”
Sarah Walworth · Google · October 2026
“The only company we trust… reliable, cost effective, and honest service from A to Z. 100% confidence in this company.”
Darrel Assink · Google · September 2026
Our Projects
1–2 of 3
Tuakau, North Waikato
Services Detection & Mapping in Tuakau
A local power network provider in Pukekohe needed expert service detection and mapping. With multiple high-voltage cables traced and marked out, duct and drainage tracing, water mains tracing and multiple communications cables in the vicinity, the project required our specialist services and expertise.
Read the case study
South Auckland
Auckland Residential Water Mains Replacement
After the aged water mains at a residential property in South Auckland had many failures, Utility Works was contracted to renew the system. The project involved services detection, concrete cutting, and hydro-vac trenching to minimise risk and damage to other services in the work zone. The new water mains were installed with a new inlet valve, toby, and relayed concrete, and the property reinstated to its original condition.
Read the case studyWorth a read first
Guides & advice
1–3 of 6
Pre-Dig Investigation in Auckland: Why It's the Most Important Step Before You Excavate
Every excavation project starts the same way — with ground that looks empty on the surface but is often anything but underneath.
Read the guide
Before You Dig in NZ: What beforeUdig Gives You and What It Doesn't
Everyone planning to dig in New Zealand is told to lodge a beforeUdig enquiry first, and they should. But the plans that come back are a starting point, not a mark-out. This guide explains what beforeUdig actually provides, where its plans fall short on real sites across Auckland and the Waikato, what professional service locating adds, and the sequence that keeps you, your crew and your budget out of trouble.
Read the guide
The Role of Underground Service Detection in Safe Excavation
Before breaking ground on any project — from residential landscaping to large-scale commercial construction — it’s vital to know what’s below the surface.
Read the guideFAQ'S
Why are pre-dig investigations necessary?
What underground services can you detect?
Do I still need to contact ‘Before You Dig’ (beforeUdig)?
Can you provide mapping for future use?
Ready when you are.
Tell us what you’re seeing or what you’re planning. You’ll get a straight answer, a free quote and one crew that does the whole job.
Mon–Fri 7am–5pm · Waiau Pa, South Auckland · Auckland, Franklin & North Waikato