Yes, in most cases you can install a simple garden irrigation system yourself — and it's a very satisfying weekend project. However, there are some important rules around connecting to your home's water supply that you need to understand before you start, particularly around what work is legally restricted in New Zealand.
What Counts as a 'Simple' Irrigation System?
A basic garden irrigation system typically includes:
- Drip irrigation lines or micro-spray heads for garden beds
- Pop-up sprinklers for lawns
- Poly pipe (usually 19 mm or 25 mm) as the main supply line
- Fittings and connectors (barbed or compression style)
- A timer/controller (battery or mains-powered)
- A backflow preventer (critical — more on this below)
These components are widely available at Bunnings and Mitre 10, and most of the installation work — laying pipe, connecting drip lines, positioning sprinkler heads — is well within a capable homeowner's ability.
Planning Your System
Good planning saves a lot of headaches. Before you buy anything:
- Sketch your garden layout and measure the area you want to irrigate.
- Check your water pressure — most residential NZ properties run at 300–500 kPa. Too much pressure can blow fittings; too little and sprinklers won't perform. A simple pressure gauge (available at hardware stores) will tell you what you're working with.
- Divide your garden into zones — lawn, garden beds, and pots often have different water needs and are best run on separate circuits.
- Choose the right emitters — drip irrigation is ideal for garden beds and water-wise planting; pop-up sprinklers suit open lawn areas.
NZ's variable climate means water-efficient design matters. Energywise has useful guidance on water conservation that's worth reading before you design your system.
The Critical Rule: Backflow Prevention
This is the most important safety and legal requirement in NZ irrigation. A backflow preventer (also called a non-return valve) must be installed between your irrigation system and the household water supply. Without it, garden water — which may contain fertiliser, pesticides, or soil — can be siphoned back into the drinking water supply under certain pressure conditions.
Under the NZ Building Code clause G12 (Water Supplies), potable water must be protected from contamination. Your local council or water supplier may also have specific requirements, so it's worth a quick call to confirm what type of backflow preventer is required for your situation.
Connecting to the Water Supply — Know the Rules
This is where homeowners need to be careful. In New Zealand, plumbing work is restricted work under the Plumbers, Gasfitters and Drainlayers Act 2006. Making a new connection to your household water supply — such as tapping into a pipe under the house or inside the wall — must be done by a licensed plumber. You can check licensing at the Plumbers Gasfitters & Drainlayers Board.
However, connecting to an existing outdoor tap (hose tap) is generally considered acceptable for a homeowner. Most simple irrigation systems are designed to connect via a standard hose thread fitting to an outdoor tap — this is the easiest and most DIY-friendly approach.
In summary:
- ✅ Connecting to an existing outdoor tap — homeowner can do this
- ❌ Installing a new tap or tapping into supply pipes — licensed plumber required
Step-by-Step: Basic Installation
1. Gather Your Materials
Poly pipe, fittings, drip emitters or sprinkler heads, a backflow preventer, a filter (recommended to protect emitters from debris), a pressure regulator if needed, and a timer.
2. Lay the Main Line
Run your main poly pipe from the tap connection along the edge of garden beds or under lawn. Use pipe staples or stakes to hold it in place. Poly pipe is flexible and easy to work with — just avoid sharp kinks.
3. Install Lateral Lines and Emitters
Use a hole punch tool to create holes in the main line, then push in barbed fittings to connect your drip lines or sprinkler risers. Space emitters according to the manufacturer's recommendations and your plant spacing.
4. Fit the Backflow Preventer and Filter
Attach these directly to the tap before the timer. The order should be: tap → backflow preventer → filter → pressure regulator (if needed) → timer → main line.
5. Programme Your Timer
Set watering times for early morning where possible — this reduces evaporation and fungal disease risk, which is especially relevant in humid northern NZ regions.
6. Test and Adjust
Turn the system on and check every emitter and fitting for leaks. Adjust sprinkler heads for coverage. Flush the system before final use.
Electrical Connections for Controllers
Battery-powered timers are the simplest option and require no electrical work. If you want a mains-powered controller or solenoid valves, any new electrical connections must be done by a registered electrician — this is restricted electrical work under NZ law. Check the Electrical Workers Registration Board to find a registered electrician.
When to Call a Professional
Consider hiring a qualified landscaper or irrigation specialist if:
- You want a multi-zone system with solenoid valves and a mains-powered controller
- You need a new tap or supply connection installed
- Your property has complex terrain, slopes, or large areas
- You're unsure about water pressure or system design
- You want the system integrated with a smart home or weather-based controller
A professional can also ensure your backflow prevention meets your council's requirements. You can find qualified local landscapers and irrigation specialists on tradedirectory.co.nz.
Licensed Building Practitioner (LBP)
