Whether your drainlayer work needs a building consent depends on what's being done — new drainage installations typically require consent, while like-for-like repairs often don't. That said, all drainlaying work (consented or not) must be carried out by, or under the supervision of, a licensed drainlayer registered with the Plumbers, Gasfitters and Drainlayers Board (PGDB). Getting this wrong can lead to failed inspections, fines, and problems when you sell your home.
What Is Drainlaying Work?
Drainlaying covers the installation, alteration, repair, or maintenance of sanitary drains and stormwater drains on your property. This includes:
- Underground pipes carrying wastewater from your house to the council sewer or septic system
- Stormwater drains directing rainwater away from your property
- Inspection chambers (manholes) and gully traps
- Connections to the public network at the property boundary
Drainlaying is restricted work under the Plumbers, Gasfitters, and Drainlayers Act 2006. Only a licensed drainlayer (or someone working under their direct supervision) may legally carry out this work. Homeowners cannot do their own drainlaying — unlike some other trades where owner-builders have limited rights.
When Is a Building Consent Required?
Under the NZ Building Code and the Building Act 2004, new drainage work generally requires a building consent. This includes:
- Installing a new drain or sewer connection for a new building or addition
- Relocating existing drains as part of a renovation
- Installing a new septic tank or on-site wastewater system
- Adding new stormwater infrastructure (e.g., soakpits, retention tanks)
- Any work that changes the layout or capacity of your drainage system
The Building Code clauses most relevant to drainage are G13 (Foul Water) and E1 (Surface Water), which set out performance requirements for how wastewater and stormwater must be managed on your site.
When Is a Building Consent NOT Required?
Schedule 1 of the Building Act 2004 lists work that is exempt from building consent. For drainlaying, common exemptions include:
- Like-for-like repair or replacement of existing drains (same location, same size, same function)
- Clearing blockages or relining pipes without altering the system
- Replacing a broken inspection chamber lid or gully trap in the same position
Important: Even exempt work must still comply with the Building Code and must be done by a licensed drainlayer. The exemption only removes the need for a formal consent — it does not lower the standard of work required.
Always check with your local council before starting any drainage work. What counts as exempt can depend on your specific situation, your council's interpretation, and whether the work touches the public network. Some councils require a Certificate of Acceptance after the fact if consent wasn't obtained.
Connecting to the Public Sewer or Stormwater Network
If your work involves connecting to (or disconnecting from) the public wastewater or stormwater network, you will almost certainly need both:
- A building consent from your territorial authority (your local council)
- A connection approval from your council's infrastructure or water services team
Your licensed drainlayer will usually manage these applications on your behalf, but it's worth confirming this upfront.
On-Site Wastewater Systems (Septic Tanks)
If your property is not connected to a public sewer, any new or replacement on-site wastewater system (septic tank, effluent disposal field, composting toilet system) will almost always require a building consent and may also require a resource consent under the Resource Management Act. Check with both your local council and your regional council. MBIE Building Performance has guidance on on-site systems.
The Inspection Process
When a building consent is issued for drainage work, your council will specify inspection stages — typically before backfilling trenches so the inspector can check pipe falls, joints, and materials. Your licensed drainlayer should coordinate these inspections. Once complete, you'll receive a Code Compliance Certificate (CCC), which is important for your property records and future sale.
For exempt work, there is no formal inspection, but your drainlayer should still issue a Certificate of Compliance confirming the work meets the Building Code.
When to Call a Professional
Because drainlaying is restricted work, you should always engage a licensed drainlayer — there is no legal DIY option here. A good drainlayer will:
- Assess whether your project needs a building consent
- Handle consent applications and council liaison
- Ensure the work meets NZS 4404 (land development and subdivision) and relevant Building Code clauses
- Arrange inspections and provide the necessary compliance documentation
You can find qualified, local drainlayers on tradedirectory.co.nz. Always check that your drainlayer holds a current licence by searching the PGDB register.
Safety Note
Drainage trenches can collapse without warning. Never enter a trench without proper shoring, and keep children and pets well away from open excavations. Your drainlayer must comply with WorkSafe NZ excavation safety requirements.
Certifying Drainlayer
