In New Zealand, most drainage work requires either a building consent or at minimum a notification to your local council before a drainlayer can legally begin. The rules depend on the type and scope of work involved, and getting this wrong can cause serious headaches — from failed inspections to issues when you sell your property.
Why Council Notification Matters
Drainage work affects public health, the environment, and the structural integrity of your property. That's why the NZ Building Code and the Building Act 2004 set clear rules about what work needs oversight. Your local council (territorial authority) is responsible for issuing consents and carrying out inspections to make sure drainage is installed correctly and safely.
The MBIE Building Performance website is the best starting point to understand your obligations under the Building Act.
When a Building Consent Is Required
Most new drainage work — including installing a new drain, connecting to the public sewer or stormwater system, or significantly altering existing drains — requires a building consent before work starts. This applies to:
- Installing new sanitary drains or stormwater drains
- Connecting a new building or addition to the public wastewater network
- Relocating or extending existing drainage lines
- Installing a new septic tank or on-site wastewater system
Your drainlayer will typically help you navigate the consent process, but the consent application is lodged by the property owner (or their agent) with the council. Work cannot legally begin until the consent is granted.
Schedule 1 Exemptions — What Doesn't Need Consent
Some minor drainage work is exempt from building consent under Schedule 1 of the Building Act. However, even exempt work must still comply with the NZ Building Code, and in many cases the council still needs to be notified before work begins.
Common examples that may be exempt include:
- Like-for-like replacement of a drain in the same location
- Minor repairs to existing drainage
- Clearing blockages
Important: Schedule 1 exemptions are interpreted differently by different councils, and the rules can change. Always confirm with your local council whether your specific job is exempt before assuming no consent is needed. Do not rely solely on this article — check with your council directly.
The Drainlayer's Legal Obligations
In New Zealand, drainlaying is restricted work under the Plumbers Gasfitters & Drainlayers Board (PGDB). This means it must be carried out by (or under the supervision of) a licensed drainlayer. It is illegal for an unlicensed person to carry out drainlaying work.
A licensed drainlayer is also required to:
- Ensure the correct consents and notifications are in place before starting
- Carry out work to the standards set by the NZ Building Code (particularly clause G13 for foul water and clause E1 for surface water)
- Arrange for council inspections at the required stages (typically before backfilling trenches)
- Provide a Certificate of Compliance upon completion of restricted work
Inspections During and After the Work
Once consent is granted and work begins, the council will usually require one or more inspections — most importantly, a pre-cover inspection before the drains are backfilled. This is critical: if you cover the drains before the inspector signs off, you may be required to dig them up again.
After the work is complete and inspections are passed, the council issues a Code Compliance Certificate (CCC), which confirms the work meets the Building Code. Keep this document safe — it's important for future property sales.
On-Site Wastewater Systems
If your property isn't connected to the public sewer, you may be installing or upgrading a septic tank or other on-site wastewater system. These almost always require a building consent and may also require a resource consent under the Resource Management Act, depending on your council's district plan and the proximity to waterways. Check with both your local council and your regional council.
BRANZ provides technical guidance on drainage and wastewater systems that both homeowners and tradespeople find useful.
What Homeowners Can and Cannot Do
Because drainlaying is restricted work, homeowners cannot legally carry out their own drainage work (unlike some other building tasks). Even if you're a capable DIYer, you must engage a licensed drainlayer. The only exception is very minor maintenance such as clearing a blocked drain with a plunger or drain snake — but any work that involves cutting, joining, or laying pipes must be done by a licensed professional.
⚠️ Safety note: Drainage work can involve confined spaces, hazardous gases (such as hydrogen sulphide in sewer lines), and deep excavations. These are serious health and safety risks. Always leave this work to qualified professionals.
When to Call a Professional
You should contact a licensed drainlayer as soon as you suspect you need drainage work done — before you contact the council, and certainly before any digging starts. A good drainlayer will:
- Assess whether consent or notification is required for your specific job
- Help prepare or advise on the consent application
- Carry out the work legally and to code
- Arrange inspections and provide the necessary compliance documentation
You can find qualified, local drainlayers on tradedirectory.co.nz.
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