Plumbing can seem straightforward, but in New Zealand the law draws a clear line between what homeowners can tackle themselves and what must be done by a licensed professional. Getting this wrong can void your home insurance, breach the NZ Building Code, and — most importantly — put your household at risk. Here's what you need to know before you pick up a spanner.
Why Plumbing Is Regulated in New Zealand
Plumbing, gasfitting, and drainlaying are restricted trades under the Plumbers, Gasfitters and Drainlayers Act 2006. The Plumbers, Gasfitters and Drainlayers Board (PGDB) oversees licensing and sets the rules for who can legally carry out this work. The intent is to protect public health and safety — poorly done plumbing can cause flooding, contamination of drinking water, or dangerous gas leaks.
The NZ Building Code — particularly clauses G12 (Water Supplies) and G13 (Foul Water) — sets the performance standards that all plumbing work must meet, whether done by a professional or a homeowner.
What Homeowners CAN Legally Do Themselves
The good news is that a fair amount of basic maintenance and minor repairs fall outside the definition of restricted work. As a homeowner, you can generally:
- Replace tap washers and O-rings on existing tapware
- Replace a showerhead (like-for-like, no pipework changes)
- Unblock drains using a plunger, drain snake, or chemical cleaner
- Replace a toilet seat
- Replace the internal components of a toilet cistern (fill valve, flush valve, flapper) without altering the supply pipework
- Reconnect a dishwasher or washing machine to existing, already-installed hose connections
- Replace tap handles or aesthetic fittings where no pipework is disturbed
- Fix minor leaks at accessible compression fittings (e.g., tightening a nut under the sink) — though if in doubt, call a plumber
The key principle: if you are not cutting, joining, or altering any pipework, and you are working on existing fittings without changing the system, you are likely in safe territory.
What Is RESTRICTED Work — Hands Off!
The following work must be carried out by a licensed plumber, gasfitter, or drainlayer (as appropriate). Doing this yourself is illegal and can carry significant penalties:
- Installing, altering, or repairing any sanitary plumbing (pipes, waste lines, vents)
- Installing or modifying water supply pipework inside or outside the home
- Installing or replacing a hot water cylinder or heat pump water heater
- Any gasfitting work — connecting appliances, installing gas lines, servicing gas water heaters (this requires a licensed gasfitter)
- Drainlaying — laying or altering underground drainage or stormwater pipes
- Installing or relocating toilets, basins, baths, or showers (anything involving new pipework connections)
- Work on backflow prevention devices
- Any plumbing work in a new build or addition requiring a building consent
A Note on Gas Work
Gas is particularly dangerous. All gasfitting is restricted work — no exceptions for homeowners. Always use a licensed gasfitter. You can verify a tradesperson's licence on the PGDB website.
Healthy Homes and Rental Properties
If you are a landlord, be aware that Healthy Homes Standards require rental properties to meet specific requirements around drainage and moisture control. Any plumbing work needed to comply must be done by a licensed professional to be legally valid.
Comparing DIY vs. Licensed Plumber
| Task | DIY Legal? | Notes |
|---|---|---|
| Replace tap washer | ✅ Yes | No pipework changes |
| Unblock a drain | ✅ Yes | Plunger, snake, or cleaner |
| Replace showerhead | ✅ Yes | Like-for-like only |
| Replace toilet seat | ✅ Yes | No tools required |
| Replace cistern internals | ✅ Yes | Don't alter supply pipe |
| Install new tapware | ❌ No | Pipework involved |
| Replace hot water cylinder | ❌ No | Restricted + consent likely needed |
| Lay new drainage pipe | ❌ No | Licensed drainlayer required |
| Any gas appliance work | ❌ No | Licensed gasfitter only |
| Install new bathroom | ❌ No | Full restricted work |
Tips for Safe DIY Plumbing
- Always turn off the water at the toby (main stopcock) before starting any work. Know where yours is before you need it.
- Keep a bucket and towels handy — even simple jobs can release residual water.
- Use quality fittings from reputable suppliers like Bunnings or Mitre 10 to ensure durability.
- If a job turns out to be more complex than expected, stop and call a professional rather than improvising.
- Check with BRANZ or your local council if you are unsure whether a job requires a building consent.
When to Call a Professional
If your job involves any pipework, gas, drainage, or a new installation, you need a licensed tradesperson. This isn't just about the law — it's about protecting your home, your family, and your insurance cover. A licensed plumber will also issue the required Certificate of Compliance (CoC) for restricted work, which you'll need for insurance claims and when you sell your home.
You can find qualified, vetted local plumbers and gasfitters on tradedirectory.co.nz — just search your region and trade.