Getting drainage work done on your property is a significant investment, and it's completely reasonable to want confidence that the job has been done properly and legally. In New Zealand, drainlaying is restricted work — meaning it must be carried out by a licensed tradesperson — and there are clear processes in place to verify compliance with the NZ Building Code. Here's what you need to know.
What Does the NZ Building Code Require for Drainage?
The NZ Building Code sets out performance requirements for all building work, including drainage. The key clauses relevant to drainlaying are:
- Clause G13 (Foul Water) — covers the safe removal of sewage and wastewater from buildings
- Clause G12 (Water Supplies) — relates to potable water, which can intersect with drainage work
- Clause E1 (Surface Water) — covers stormwater drainage and management
These clauses don't prescribe exactly how work must be done, but they set the outcomes that must be achieved — things like preventing contamination, ensuring adequate flow, and protecting public health. Compliance is typically demonstrated by following acceptable solutions or verification methods approved by MBIE Building Performance.
Is Drainlaying Restricted Work in NZ?
Yes. Under the Plumbers, Gasfitters, and Drainlayers Act 2006, drainlaying is restricted work that must be performed by a person licensed or supervised by a licensed drainlayer. This is non-negotiable — unlicensed drainlaying is illegal and can result in serious health and safety risks, as well as significant liability for the property owner.
You can verify your drainlayer's licence through the Plumbers Gasfitters & Drainlayers Board (PGDB). Simply search their online register using the tradesperson's name or licence number before work begins.
Does the Work Need a Building Consent?
Many drainage jobs require a building consent from your local council before work starts. This is one of the most important steps in ensuring compliance. Consented work is inspected by a council building inspector at key stages, giving you an independent check that the work meets the Building Code.
Some minor drainage work may be exempt from consent under Schedule 1 of the Building Act 2004, but the rules around this are specific and can vary by council and situation. Always check with your local council before assuming consent isn't needed — getting this wrong can cause major headaches when you sell your property or make a claim.
You can find general guidance on consents and exemptions at MBIE Building Performance.
What Inspections Should Happen?
If a building consent is required, your council will specify inspection stages that must be passed before work is covered over. For drainage, this typically includes:
- Pre-cover inspection — the inspector checks pipe grades, depths, materials, and connections before trenches are backfilled
- Final inspection — confirms all work is complete and a Code Compliance Certificate (CCC) can be issued
Never allow a drainlayer to backfill trenches before the required inspection has been passed. If you're unsure whether an inspection has been booked, ask your drainlayer directly — it's your right to know.
What Is a Code Compliance Certificate?
A Code Compliance Certificate (CCC) is issued by your council once all inspections are passed and the work is confirmed to meet the Building Code. This is your official proof of compliance and is an important document to keep safe — it will be needed if you sell or refinance your property.
How to Check Your Drainlayer's Work Yourself
While you shouldn't be expected to technically assess drainage work, there are some practical things you can look out for:
- Ask for the consent and inspection records — a reputable drainlayer will have no issue providing these
- Check the PGDB register to confirm your tradesperson is licensed
- Look for a CCC once the job is complete — if one isn't issued, find out why
- Watch for warning signs after completion: slow drains, gurgling sounds, wet patches in the yard, or unpleasant smells can indicate problems
- Ask for a producer statement — for larger jobs, your drainlayer may provide a PS3 (construction review) confirming the work was done to the design
What Standards Apply to Drainlaying Work?
Drainlayers typically work to NZS 4404 (Land Development and Subdivision Infrastructure) and other relevant New Zealand Standards for pipe materials and installation. Your council's district plan and infrastructure standards may also impose additional requirements. Standards NZ is the place to look up specific standards if you want to dig deeper.
BRANZ also publishes research and guidance on building performance that can help homeowners understand what good practice looks like.
When to Call a Professional
If you have concerns about drainage work that has already been completed — especially if it was done without consent or by an unlicensed person — you should:
- Contact your local council to discuss the situation and understand your options
- Engage a licensed drainlayer to inspect the existing work and advise on remediation
- Contact the PGDB if you believe a licensed tradesperson has done substandard or non-compliant work — they handle complaints about licensed practitioners
For new drainage work, always use a qualified, licensed drainlayer. You can find trusted local drainlayers on tradedirectory.co.nz.
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