In New Zealand, drainage work is tightly regulated to protect public health and the environment. Most work involving drains that connect to the public sewer or stormwater system must by law be carried out by a licensed drainlayer — and getting this wrong can result in fines, failed inspections, or serious health hazards. Here's a clear breakdown of what's restricted, what isn't, and when to call in a professional.
Why Drainage Work Is Regulated
Drainage systems carry wastewater and stormwater away from your home and into the public network. Poorly installed or repaired drains can cause sewage contamination, flooding, and structural damage. To manage these risks, the Plumbers, Gasfitters and Drainlayers Act 2006 makes certain drainage work restricted work — meaning only a licensed or certifying drainlayer can legally carry it out.
The Plumbers Gasfitters & Drainlayers Board (PGDB) is the licensing authority that registers and oversees drainlayers in New Zealand. Always check that your drainlayer holds a current licence before work begins.
What Is Restricted Drainage Work?
Restricted work under the Act includes any work on sanitary drains and stormwater drains that form part of, or connect to, the public wastewater or stormwater network. Specifically, this covers:
- Installing new drains — laying new underground pipework from your house to the boundary or beyond
- Connecting to the public sewer or stormwater system — any tie-in to the council's network
- Repairing or replacing existing drains — including broken, cracked, or root-damaged underground pipes
- Installing or altering septic tanks and on-site wastewater systems — these must comply with the NZ Building Code (specifically clause G13: Foul Water) and usually require a building consent
- Installing stormwater systems — downpipe connections, soakpits, and underground stormwater drains
- Drain relining or pipe bursting — trenchless repair methods on sanitary or stormwater drains
- Installing inspection chambers and manholes — any access points on restricted drain lines
If work is restricted, only a licensed drainlayer (or someone working under their direct supervision) can legally do it. The completed work must also be certified by a certifying drainlayer.
What About Building Consents?
Many drainage jobs also require a building consent from your local council before work starts. This typically applies to:
- New drainage installations
- Alterations to existing drainage systems
- On-site wastewater systems (septic tanks, treatment units)
Some minor repairs may fall under Schedule 1 of the Building Act 2004 as exempt work, but this is not always straightforward. Always check with your local council before assuming consent isn't needed. You can find general guidance at MBIE Building Performance.
What Can a Homeowner Do Themselves?
As a homeowner, there is very little drainage work you can legally do yourself without a licence. However, you may generally:
- Clear a blocked drain using a plunger or drain snake on internal fixtures (sinks, toilets, showers)
- Clean or unblock a gully trap at ground level
- Maintain surface drainage such as clearing leaves from open channel drains or surface grates
- Replace a broken gully trap grate (the cover only, not the trap itself)
Anything that involves digging up, cutting into, or connecting underground pipework is almost certainly restricted work. If in doubt, contact the PGDB or your local council for clarification before you start.
On-Site Wastewater Systems: Extra Rules Apply
If your property is not connected to the public sewer — for example, rural properties using a septic tank or treatment system — the rules are just as strict. Installation, alteration, and maintenance of these systems must be done by a licensed drainlayer, and the system must comply with NZ Building Code clause G13 and relevant standards. Your council's environmental health team may also have specific requirements around discharge consents under the Resource Management Act.
Stormwater: Don't Overlook It
Stormwater drainage is often overlooked, but it is equally regulated. Connecting a new downpipe to an underground stormwater drain, installing a soakpit, or altering your property's stormwater system all count as restricted work. Poorly managed stormwater can cause flooding on your property and your neighbours', and may breach NZ Building Code clause E1: Surface Water.
Penalties for Unlicensed Work
Carrying out restricted drainage work without a licence — or allowing unlicensed work to be done on your property — can result in:
- Fines under the Plumbers, Gasfitters and Drainlayers Act
- Failed building inspections and difficulty getting a code compliance certificate
- Insurance issues if damage results from unlicensed work
- Potential liability if the work causes harm to others
When to Call a Professional
Call a licensed drainlayer any time you need to:
- Repair, replace, or install underground drains
- Connect to the public sewer or stormwater network
- Install or alter a septic tank or on-site wastewater system
- Investigate a persistent blockage that may involve underground pipework
- Carry out drainage work as part of a renovation or new build
A qualified local drainlayer will know your council's requirements, pull the right consents, and certify the work correctly. You can find licensed drainlayers in your area right here on tradedirectory.co.nz.
Certifying Drainlayer
