Blocked drains, soggy lawns, and slow-draining sinks are frustrating — and it's tempting to grab a spade and sort things out yourself. But in New Zealand, a significant amount of drainlaying work is legally restricted, meaning only a licensed professional can carry it out. Getting this wrong can result in fines, failed building inspections, and serious health risks for your household and neighbours.
What Is Restricted Drainlaying Work?
Under the Plumbers, Gasfitters and Drainlayers Act 2006, drainlaying is a licensed trade regulated by the Plumbers, Gasfitters and Drainlayers Board (PGDB). Restricted drainlaying work covers the installation, alteration, repair, or replacement of any drain that:
- Connects to the public sewer or stormwater network
- Forms part of an on-site wastewater system (e.g. septic tank, effluent disposal field)
- Carries sewage or wastewater from a building to a point of disposal
- Involves sanitary plumbing below ground level
In plain terms: if it carries waste or sewage, or connects to the council network, a licensed drainlayer must do the work.
What Qualifications Must a Licensed Drainlayer Hold?
A Licensed Drainlayer (LD) must be registered and hold a current practising licence issued by the PGDB. Always ask to see their licence or check the PGDB licence register before work begins. Unlicensed people who carry out restricted work face significant penalties under the Act.
Common Jobs That Require a Licensed Drainlayer
Here are typical residential jobs that must be done by a licensed drainlayer:
- Installing or replacing sewer drain pipes from your house to the boundary or council main
- Connecting a new bathroom, toilet, laundry, or kitchen to the existing drain system
- Installing or modifying a septic tank, treatment unit, or effluent disposal field
- Repairing a cracked or collapsed sewer line underground
- Installing stormwater drains that connect to the council network
- Any drainwork required as part of a building consent (e.g. new extension, sleepout with plumbing)
- Drain camera inspections followed by remedial work on restricted pipes
- Installing grease traps or trade waste connections
What Can a Homeowner Do Themselves?
There is a narrow range of drain-related tasks homeowners can legally carry out on their own property without a licence:
- Unblocking drains using a plunger, drain snake, or high-pressure water jetter (hired equipment)
- Cleaning and maintaining gully traps and surface grates
- Replacing a broken gully trap grate (the grate only, not the trap body connected to the drain)
- Basic surface-level stormwater management such as redirecting downpipes into a rain barrel (where permitted by your council)
- Maintaining subsoil drainage (agricultural-style drainage that does not connect to the sewer or stormwater network)
If you are ever unsure whether a job crosses into restricted territory, contact the PGDB or your local council before you start.
How Does the NZ Building Code Apply?
Most drainlaying work that requires a building consent must also comply with the NZ Building Code, particularly Clause G13 (Foul Water) and Clause E1 (Surface Water). Your licensed drainlayer will be familiar with these requirements and will ensure the work is inspected and signed off correctly. BRANZ publishes good practice guidance that drainlayers and builders use alongside the Building Code.
Do You Always Need a Building Consent for Drain Work?
Not always — minor like-for-like repairs to existing drains may be exempt, but any new connection, extension, or alteration to a sanitary drain generally requires both a building consent and a licensed drainlayer. Check with your local council's building department first.
Penalties for Unlicensed Drainlaying
Carrying out restricted drainlaying work without a licence is an offence under the Plumbers, Gasfitters and Drainlayers Act. Penalties can include substantial fines. Beyond the legal risk, unlicensed work may:
- Void your home insurance if a claim arises from the work
- Cause your property to fail a pre-sale LIM report or building inspection
- Create public health hazards from sewage contamination
- Result in council enforcement action requiring costly remediation
Comparison: Licensed vs DIY Drain Tasks
| Task | Licensed Drainlayer Required? |
|---|---|
| Unblocking a drain with a plunger | No — DIY is fine |
| Replacing a sewer pipe underground | Yes — restricted work |
| Connecting a new toilet to the drain | Yes — restricted work |
| Cleaning a surface gully trap grate | No — DIY is fine |
| Installing a septic tank system | Yes — restricted work |
| Redirecting a downpipe to a rain barrel | Generally no — check with council |
| Repairing a cracked underground sewer | Yes — restricted work |
| Hiring a water jetter to clear a blockage | No — DIY is fine |
When to Call a Professional
If your job appears anywhere in the "restricted work" list above, stop and call a licensed drainlayer. You should also call a professional if you notice:
- Sewage smells inside or outside your home
- Multiple drains backing up at once (sign of a main drain blockage or collapse)
- Wet patches or sinkholes in your lawn near drain lines
- Slow drainage that doesn't respond to basic unblocking
A qualified local drainlayer can carry out a CCTV drain inspection to pinpoint the problem before any digging begins. You can find licensed drainlayers in your area through tradedirectory.co.nz.