How long should you run your irrigation for?

Do you know how long to run your irrigation for and how many days a week to water? 

As a general guide, in the dry season Living Water Smart recommends the below 3, 2, 1 guide for efficient watering:

  • Three days a week for lawn.
  • Two days a week for exotics such as fruit trees and palms.
  • One day a week or less for native plants and trees such as acacias, grevilleas and eucalypts.

Give your plants and lawn 10 mm of water each time you irrigate and generally about 30 mm of water over a week. Keep an eye on the Weather Web to find out how much rain your suburb has received.  

There are many different types of sprinklers, including fixed spray, single-stream rotors or multi-stream rotors, and drippers.  Each type of sprinkler applies water at different rates, making it hard for you to work out how long to water your lawn and plants to reach the recommended 10 mm of water.

A catch can test can help; you can use it to determine how long to run your irrigation system or sprinkler for and how even water is distributed over your lawn or garden. 

You could use a specially made sprinkler catch can, which are available from local irrigation and hardware stores or online, or tuna or cat food cans work well too. 

Catch can

Tuna can

Catch Can Test

Follow the steps below to determine the run time of your irrigation system:

Step 1:  Place a few catch cans evenly across the irrigated area (in a grid like pattern) and run your irrigation for 10 minutes.

Step 2:  Record the amount of water captured in each of your catch cans (tip: if using a tuna can, use a ruler placed into the centre of the can and record in millimetres).  Add all the amounts together and then divide by the number of catch cans you are using to get an average amount of water per catch can.  Write this figure down.  

To find out how many minutes to run your irrigation, you just need to divide 100 by the figure you have written down (the average amount of water per catch can).  To help you, just put your written down figure, the average, in the calculator below:

Calculator

100 divided by

= 0 minutes


Here are some examples:

  • If you record an average of 10 mm of water in your catch can after watering for 10 minutes, divide 100 by 10 which will give you an irrigation run time of 10 minutes. 
  • If you record an average of 5 mm of water in your catch can after watering for 10 minutes, divide 100 by 5 which will give you an irrigation run time of 20 minutes. 
  • If you record an average of 2 mm of water in your catch can after watering for 10 minutes, divide 100 by 2 which will give you an irrigation run time of 50 minutes.

Step 3:  Check if the water levels in all the catch cans are equal or near equal.  This will tell you if your irrigation system is distributing water evenly.  If it’s not, you may be able to adjust your sprinkler heads or nozzle size to distribute the water more evenly.  Or you may need to change the placement of your sprinklers to ensure the coverage of your lawn of garden is even. 

Watch and adjust
Keep an eye on your garden over the next week. If it is looking thirsty, or water logged, then change your watering time by 5 minutes.  Give it another week and if your garden is still not thriving, change the times again until you and your garden are happy.

Get a Garden Tune Up
There are other factors to take into consideration when analysing sprinkler run times, such as your flow rate and operating pressure, the size and height of the nozzle and the spray arc of the emitter.  You should also consider hydrozoning, soil types and mulch, climate and plant types when determining how much water your garden needs. 

We recommend you engage a professional irrigator to help you get your garden irrigation just right.  Living Water Smart offers a free Garden Tune Up service with a registered irrigator who will audit your irrigation system and provide advice about how to best achieve a water efficient irrigation system and healthy, happy garden. They will also make minor on the spot repairs up to the value of $50.

Living Water Smart's Garden Tune Up provides a free garden irrigation audit at your home or business by one of our registered irrigation experts. The irrigator will reprogram your irrigation controller to provide your garden with the water it needs, when it needs it. It also includes up to $50 of on-the-spot irrigation repairs.