Home > Saving water > In your garden > Watering systems

Watering systems

Drip irrigation is the most efficient watering method around, proving that low flow is the way to go. Hardly any water is wasted through wind, evaporation, run-off or overspray.

Did you know that it can take 15 minutes to deliver just one litre of water to the soil with drip irrigation, compared to five seconds when delivering one litre by hand?

By slowly dripping water into the soil at the base of plants, water is released at a rate that's easy to absorb, only where it's needed. After all, why water the weeds?

Drip irrigation also reduces the risk of erosion, soil compaction and insect and fungal problems in plants. It's great for all garden areas

Benefits of drip irrigation

uses flexible piping that is easily laid and suitable for most environments, including ornamental gardens
ideal for windy areas as the water goes directly to plants roots
great for everything from plants on slopes to vegetable gardens
suits all soil types
suits all plant types
reduces the risk of plant fungal and insect problems (only wets the soil around the plants roots, not the leaves)
causes less erosion and soil compaction
loses the least amount of water from wind, evaporation and run-off
can be used to apply liquid fertiliser to gardens (you must use a backflow prevention device to ensure fertilisers don't go back into the drinking water supply)
doesn't waste water on weeds.

Drip irrigation components

Integrated drip line (piping or tubing)

Integrated drip line irrigation is usually made from PVC and varies in diameter, depending on the amount of water pressure required. It can be laid either above or below the soil surface or in a layer of mulch. While more water pressure is required for longer piping and extra emitters, it's important to remember that extra pressure will not water your plants more effectively.

Drip emitters

Drip emitters attach to standard PVC irrigation piping and apply a consistent amount of water to your garden plants. As a general rule, cheaper and less sophisticated emitters (which are not recommended) have highly variable flow rates that depend on water supply pressure while commercial quality emitters have pressure-compensating systems to ensure a constant flow rate.

Weeping hoses

Weeping hoses are usually made of black recycled type rubber. They can be attached to a fixed watering system or an ordinary garden hose. As with integrated drip lines, weeping hoses can be laid either above or below the soil surface or in a layer of mulch. While more water pressure is required for longer hoses, weeping hoses work most effectively at low pressures.

Controllers

Controllers are used to manage the flow of water through your drip irrigation system. Simple controllers, such as a mechanical tap timer, only require you to set the amount of watering time. More complex electronic controllers can water different garden zones at different times and even different days. Consult your local irrigation supplier for more information.

Backflow prevention device

Backflow occurs when there is a reverse pressure in the water supply system, drawing contaminants like fertilisers and other garden chemicals back into the drinking water supply through installed irrigation system. Installing a backflow prevention device can prevent serious injuries caused by contaminated water.

Rain switches

A rain switch will turn off your drip irrigation system during wet weather, preventing over watering and saving you money. A rain switch can be connected to most electronic automatic controllers.

Soil moisture sensors

Soil moisture sensors are placed beneath the soil surface at a specified depth around your garden to measure the amount of moisture in the soil. When the moisture level drops below a predetermined level it allows the irrigation controller to operate, watering your garden. A soil moisture sensor can be fitted to most electronic automatic controllers.

Joints and connectors

T-joints, elbows, couplers and end caps connect the piping in your irrigation system.

Designing an effective drip irrigation system

The following hints may help in the planning and design of your drip irrigation system.

Work out the number of connectors needed when planning your drip irrigation system.
Plants in sunny areas usually require more water due to higher evaporation rates. Plants in shaded areas will require less water due to lower evaporation rates.
Note slopes and soil types to help work out the watering requirements for different areas of your garden. For example, gardens with heavy clay soil may need more water pressure.
Select drip emitters according to your plants' watering requirements.
Consider where you would need joints and connectors.
Rain switches and soil moisture sensors are highly recommended, especially in areas with high rainfall.
Lay the piping above ground before digging. A 10 centimetre deep trench should be adequate, although sandy soil may require a slightly deeper trench to hold the piping in place.
To make it easier to connect joints, heat the end of your piping to soften it and make it more flexible.
Make sure drip emitters are installed above ground so that they do not become clogged by dirt.

Watering schedule

An adequate watering schedule is the most important aspect of any irrigation system.

Consider local rainfall levels and soil type to work out the amount of water your garden needs.
Soil moisture sensors can be used to manage the scheduling of your automatic controller.
Rain switches turn off your watering system when it's raining.
Due to their established root system, mature plants need less water than new plants.
It is also a good idea to sort plants into different watering zones and water them accordingly.
By choosing plants to suit your local environment, you can save water and ongoing costs in your garden.