Installing a new dishwasher or washing machine seems straightforward — plug it in, connect a hose, and away you go. In many cases that's close to the truth, but NZ law draws a clear line between what you can do yourself and what must be handled by a licensed professional. Getting it wrong can void your home insurance, breach the NZ Building Code, or cause a costly water leak. Here's what you need to know before you start.
What Does NZ Law Say About Plumbing Work?
Under the Plumbers, Gasfitters and Drainlayers Act 2006, sanitary plumbing work — which includes making new connections to your home's water supply pipes or waste/drain system — is restricted work. This means it must be carried out by, or under the supervision of, a licensed plumber registered with the Plumbers, Gasfitters and Drainlayers Board (PGDB).
However, the law does allow homeowners to do certain like-for-like appliance connections themselves, provided no new pipework is involved. The key distinction is whether you are:
- Connecting to existing, already-installed fittings (generally OK for a homeowner), or
- Installing new supply pipes, waste pipes, or modifying existing pipework (restricted — needs a licensed plumber).
Installing a Washing Machine: What You Can DIY
A top-loader or front-loader washing machine typically connects to:
- A cold water tap (and sometimes a hot water tap) via a flexible hose
- A standpipe or laundry tub for the drain hose
- A standard 230V power outlet (see electrical note below)
If your laundry already has a dedicated washing machine tap and a standpipe or tub in place, swapping out an old machine for a new one is generally something a homeowner can do. You're simply:
- Turning off the tap, disconnecting the old hoses, and reconnecting new ones
- Hooking the drain hose over the standpipe or into the tub
- Plugging into the existing power outlet
Always check hose washers are in good condition and fittings are hand-tight plus a quarter turn — over-tightening can crack fittings.
Installing a Dishwasher: It Depends on the Setup
Dishwashers are a little more involved. A standard underbench dishwasher needs a cold water supply connection, a drain connection (usually into the sink waste or a dedicated standpipe), and a power outlet.
| Scenario | DIY OK? | Notes |
|---|---|---|
| Replacing existing dishwasher, same connections | Generally yes | Reuse existing tap, waste fitting, and power outlet |
| First-time install with existing tap & waste fitting | Possibly — check first | If fittings are already there and accessible, connection may be DIY |
| New install requiring new supply pipe or waste pipe | No — restricted work | Must use a licensed plumber |
| Modifying cabinetry or drainage routing | Plumbing part is restricted | Cabinetry work is DIY; pipework is not |
If your kitchen has never had a dishwasher, a plumber will almost certainly need to install a dishwasher outlet valve on the supply pipe and a waste connection on the sink trap — both are restricted plumbing tasks.
Electrical Connections: A Separate Consideration
Both appliances need a power supply. In NZ, electrical wiring work is restricted under the Electricity Act and must be done by a registered electrician licensed with the Electrical Workers Registration Board (EWRB).
However, plugging an appliance into an existing, correctly rated power outlet is not restricted — that's simply using the outlet as intended. What you cannot do yourself is install a new outlet, move an existing one, or run new wiring.
Safety note: Always ensure the power is switched off at the wall before connecting or disconnecting any appliance. Never operate a washing machine or dishwasher with a damaged power cord.
Avoiding Common Mistakes
- Don't overtighten hose connections — use a washer and hand-tighten firmly. Cracked plastic fittings are a common cause of slow leaks inside cabinetry.
- Check the drain hose height — most manufacturers require the drain hose to loop up to a certain height before dropping to the waste connection. This prevents backflow. Check your appliance manual.
- Use braided stainless hoses where possible — they're more durable than plain rubber hoses and less likely to burst.
- Test for leaks before pushing the appliance back into its cavity. Run a short cycle and check all connections carefully.
- Check your home's water pressure — BRANZ notes that high water pressure can stress hose connections over time. If you're unsure about your pressure, a plumber can check it.
NZ Building Code Considerations
The NZ Building Code clause G12 (Water Supplies) and clause G13 (Foul Water) govern how water supply and drainage must be installed in your home. Any work that modifies these systems needs to comply — and if it's restricted work done without a licensed plumber, it may not be covered by your home insurance if something goes wrong.
If you're a landlord, note that the Healthy Homes Standards require rental properties to have adequate drainage and moisture control — a leaking appliance connection could put you in breach.
When to Call a Professional
Call a licensed plumber if:
- You're installing a dishwasher or washing machine for the first time and no supply tap or waste connection exists
- You need to move or extend any water supply or drain pipes
- You're unsure whether existing fittings are suitable or up to code
- You notice low water pressure, slow drainage, or signs of existing leaks
- You're doing a renovation and want everything done properly with a Certificate of Compliance
A qualified local plumber can also advise on the best setup for your specific home. You can find licensed plumbers in your area at tradedirectory.co.nz.