Garden watering systems

Hand-watering versus automatic irrigation

Hand-watering

When a garden is watered by hand, the risk of over-watering is low. You quickly notice when the soil stops absorbing water as water starts to flow sideways. It's easy to identify which plants look more stressed than others, and change watering habits as seasons change.

Automatic irrigation

Automatic irrigation systems are an efficient way to water gardens. However, they're not a set-and-forget option. If they're not well designed, programmed and maintained, they can use more water than a garden needs .

That's why it's important to carefully consider what irrigation system that's right for your garden before you have it installed. We recommend you have an irrigation professional help design it. Once it's operating, you'll need to maintain to help it work well and keep your garden healthy.

Get good irrigation design advice

If you've decided an irrigation system is right for you, get the best advice. The right level of training and skill may not be available from your local hardware store or nursery. In Greater Sydney, the best place to get expert irrigation advice is at shops that sell irrigation systems.

Specialist shops often employ certified professionals who are happy to help, and their advice is usually free. Come prepared with some basic information. Staff may be able to offer expert advice to guide you through everything you need to set up a high-quality system yourself. If you'd prefer to have an expert visit your home, it can cost more.

Start with a plan

Your garden's layout and water supply will shape your irrigation system. If you go to a specialist irrigation shop, take a simple plan of your garden. Professional irrigators usually draw a scale plan. A scale of 1:100 works well for most gardens.

Lawn areas, garden beds, vegetable patches and tree groups all need different amounts of water. Treat each area as its own watering zone. A good irrigation system lets you water each zone separately. This helps you save water and keep your garden healthy. Take photos of each area to make it easier for an irrigation expert to give you the right advice.

Know your water flow rate

No matter how your system is controlled, it's important to know your flow rate – or how much water your garden will receive each time it's watered.

Once you know your flow rate, you can compare it with the flow rates of irrigation fittings. Sprays use the most water, while drippers use the least. You can work out the maximum number of sprays, nozzles or drippers you can install in each irrigation zone. A specialist irrigation retailer can help you find commercial-grade irrigation fittings with the specific flow rates you need using Water Wise Guidelines.

How to calculate your flow rate

All you need is a bucket and a stopwatch. Make sure you know how many litres of water your bucket holds when full.

• Turn on your garden tap as hard as it will go.
• Time how long it takes to fill your bucket.

For example, if it takes 15 seconds to fill a 9 litre bucket, the flow rate is 36 litres per minute.

Choose the right irrigation controller

Each irrigation zone in your garden should be watered separately. This lets you choose how often and how long to water each area.

How long to water depends on:

• how much water your soil can hold
• how fast your irrigation system delivers water.

Once you know how long it takes to water, it won't change unless you improve your soil. How often to water depends on the type of plants you have and the local weather and seasons. You may need to adjust how often you water based on the time of year.

About the controller

The controller is the core of an irrigation system. The best residential irrigation systems use a combination of weather data and sensors. Control valves allow water to flow to each irrigation zone at a frequency that matches the rate that water is lost from each garden zone. Time is manually set based on your soil's ability to store water and the irrigation rate.

Ideally, look for an irrigation controller that senses when it has rained. The most efficient options are weather-based controllers that use your home's wi-fi to capture free local weather data from the Bureau of Meteorology (BOM). These systems can even turn off future irrigation on days when rain is predicted with near certainty. Optional soil moisture sensors can give the controller additional feedback.