Why drip suits a vegie patch
- Less waste. Colorado State University Extension rates drip at over 90 % efficiency and sprinklers at 50–70 %. Less water is lost to wind, evaporation and paths.
- Dry leaves. Water goes to the soil, not the foliage, which matters for crops prone to leaf diseases such as tomatoes and cucurbits.
- Under mulch. Dripline works under straw or sugar-cane mulch. Yarra Valley Water calls sub-surface drip on a timer, running overnight, the most efficient and effective watering system.
- More watering hours. In Sydney, drip and smart systems may run in the middle of the day when sprinklers may not (see the rules below).
The parts, in order
| Part | What it does | What to look for |
|---|---|---|
| Tap timer | Runs the system while you're away or asleep | Set by minutes and days; battery or solar |
| Pressure reducer | Drops mains pressure to what drip is made for | Holman's 13 mm reducer takes up to 800 kPa in and delivers 180 kPa |
| Filter | Stops grit blocking the tiny dripper outlets | 150 mesh (Clemson University); 150–200 mesh for town water (Colorado State) |
| 13 mm poly pipe | Carries water from the tap to the beds | Joiners, elbows and tees to suit |
| Dripline | Tube with drippers built in, laid along rows | Pope Drip Eze: 2 L/h at 100 kPa. Holman Techline: 3 L/h every 300 mm |
| 4 mm tube and button drippers | Individual drippers for pots, shrubs and trees | Antelco pressure-compensating drippers: 2, 4 or 8 L/h |
| End plugs or flush valves | Close the ends and let you flush out sediment | One at the end of every line |
Holman puts the reason for the reducer and filter plainly: drippers emit water from tiny outlets, need filtered water, and stop working when they block. Colorado State suggests an operating pressure of 20–30 psi, about 140–210 kPa, and Clemson about 30 psi. Pressure-compensating drippers hold their flow steady along long or sloping runs.
Laying it out
How far water spreads sideways from a dripper depends on the soil. It runs straight down in sand and spreads wide in clay. Colorado State's spacings are:
| Soil | Drippers apart |
|---|---|
| Sandy | about 30 cm (12 in) |
| Loam | about 45 cm (18 in) |
| Clay | about 60 cm (24 in) |
- Lines per bed. In a 1.2 m wide raised bed, three lines about 40 cm apart cover the width. Pope says its Drip Eze wets a strip up to 50 cm either side of the tube, which varies with the soil. Lay the lines, run them, then dig a little to see how far the water has spread before planting.
- Run length. Keep each line within the length printed on the packaging, and a zone's supply pipe under about 60 m (200 ft), as Colorado State advises.
- Slopes. Colorado State adds 5 psi, about 35 kPa, for every 10 ft (3 m) of rise. On a slope, use pressure-compensating dripline or drippers.
- Mulch on top. Peg the lines down, then mulch over them. See which straw mulch suits a vegie bed.
How long to run it
A dripline's application rate, in millimetres an hour, is the dripper flow divided by the area each dripper serves:
| Dripline | mm per hour | Minutes for 10 mm |
|---|---|---|
| 2 L/h every 30 cm, lines 30 cm apart | 22 | 27 |
| 2 L/h every 30 cm, lines 40 cm apart | 17 | 36 |
| 3 L/h every 30 cm, lines 40 cm apart | 25 | 24 |
| 2 L/h every 30 cm, lines 50 cm apart | 13 | 45 |
How much a vegie bed needs depends on the weather. As a rough guide, about 15–25 mm a week in spring and autumn, and 30–40 mm or more in a midsummer heatwave, as the rainwater tank calculator explains. The watering calculator turns your dripline or drippers into minutes and litres. For individual drippers, it works in litres per plant instead.
When you're allowed to run it
Water rules change with droughts and dam levels, so check your water supplier before setting the timer. The permanent rules at the time of writing:
- Sydney: sprinklers and watering systems only before 10 am and after 4 pm, but Sydney Water allows smart watering systems and drip irrigation between 10 am and 4 pm as well.
- Melbourne and Victoria: watering systems only between 6 pm and 10 am; hand-held hoses, watering cans and buckets at any time.
- Perth: Water Corporation's roster allows watering once, before 9 am or after 6 pm, on your rostered days. Check its site for how the roster applies to drip.
Elsewhere in Australia and in New Zealand, councils and water suppliers set restrictions when they are needed, so check their websites in a dry summer.
Keeping it working
- Each spring, flush the lines and clean the filter before the first run, as Colorado State recommends.
- Walk the beds while the system runs every few weeks. A dry patch means a blocked dripper; a puddle means a split or a missing plug.
Questions
How long should I run drip irrigation in a vegie garden?
Long enough to put down the millimetres you want, which depends on your dripline. A 2 L/h dripline with drippers every 30 cm, in lines 40 cm apart, applies about 17 mm an hour, so 10 mm takes about 36 minutes. Divide the dripper flow by the area each dripper serves to get your own rate.
How far apart should drippers be?
About 30 cm in sandy soil, 45 cm in loam and 60 cm in clay, according to Colorado State University Extension. Water spreads further sideways in heavier soil, so the drippers can be further apart.
Do I need a pressure reducer and filter for drip irrigation?
Yes, on mains water. Drip runs at about 140–210 kPa, well below mains pressure, and drippers block easily, so a reducer and a 150 mesh filter go between the tap and the pipe. Holman's combined unit, for example, delivers 180 kPa.
Can I run drip irrigation in the middle of the day?
In Sydney, yes: Sydney Water allows drip and smart systems between 10 am and 4 pm. In Victoria, watering systems may only run between 6 pm and 10 am. In Perth, the watering roster applies. Rules change with water levels, so check your supplier.
Sources
- Colorado State University Extension, Drip irrigation for home gardens (fact sheet 4.702) – efficiency, emitter spacing by soil, filter mesh, pressure, elevation, zone length, run time, maintenance.
- Clemson University HGIC, Landscape irrigation equipment: filters and pressure regulators – 150 mesh filter, about 30 psi.
- Holman, 13 mm pressure reducer with filter assembly and Techline PC drip tube; Pope, Drip Eze tube; Antelco pressure-compensating button drippers.
- Sydney Water, Water Wise Guidelines; Yarra Valley Water, Permanent water saving rules; Water Corporation, Check your watering days.
Last reviewed 24 September 2026 · Report an error