Lawn Irrigation – The Basics

If you’re planning a new lawn, why not take the extra time to plan a bit of irrigation to go with it? Irrigation is a comparatively cheap addition to your project and it will make a world of difference to your long term maintenance program.

Irrigation, when installed correctly can not only save you time but is in fact a water-wise solution, as there is less water wastage due to a more even and better directed application.

To start, firstly to map out your area, mark where each tap point is and comprehend what will be covered from each point. Once you have a rough idea of what needs water and from where you will need to know how much water you have available. To do this you will need to conduct “The Bucket Test”.

• Grab a standard 9L household bucket.
• Turn your tap on to maximum flow.
• Place you bucket directly under your flowing tap.
• With a stop watch, time how long it takes to fill the bucket.

Bucket Size (Litres) ÷ Time (Seconds) = Flow Rate Litres/Second

 

Flow Rate Litres/Second x 60 x 60 = Flow Rate Litres/Hour

 

It is best to use a rate of around 80% of this figure. This ensures you will have sufficient pressure to propel from the sprinklers.

 

It’s important to understand that you will not be able to water your entire yard from the one small tap point. You will need to break up your space into zones to allow adequate flow through each point.

Once you have conducted the bucket test above, you can then determine how many zones you will need based on your desired sprinkler. For example, if you are using a sprinkler that has a flow rate of 8 Litres/Minute and your tap point is capable of 30 Litres/Minute (24 Litres/Minute at 80%), then you will be able to effectively run three sprinklers from this tap at the one time. Check out the basic example of a mapped garden with sprinkler placement.

In this design we have mapped the area using 3 metre radius lawn popups with a flow rate of approximately 4 Litres/Minute at 180 degrees and 2 Litres/Minute at 90 degrees. In this example the total flow demand is 50 Litres / Minute (1 sprinkler at 270 degree, 10 sprinklers at 180 degrees and 3 sprinklers at 90 degrees). Assuming our tap points both produce the maximum recommended output of 30 Litres/Minute at 180 degrees (24 Litres/Minute at 180 degrees at 80%) we require two tap points to zone and cover the entire area effectively.

Notice the design places the sprinklers no more than 3 metres apart in all directions allowing for overlap in the spray and effective complete coverage. In larger or wider areas you may need a secondary run of 360 degree sprinklers down the centre and in non-square designs you can adjust the spray circle from 180 degrees up to the desired angle.

The 3 main sections of an irrigation system are:

• The Water supply.
• Sprinkler Zone control either Manual or Automatic.
• The watering zone which includes sprinklers, sprinkler pipe and fittings.

Some basic rules to guide you include:

• Makes sure to never exceed 80% of your available water flow-rate from a tap point. The remaining 20% of pressure goes towards propelling the water.
• Don’t exceed a 30 Litres/Minute flowrate for a 19mm pipe. Flow rates exceeding 30 Litres/Minute may cause blowouts.
• The best layout is a head-to-head layout on a lateral run. A head-to-head layout means sprinklers with a 3 metres radius are spaced no more than 3 metres apart which creates a 100% overlap.
• Keep similar sprinklers together within a zone for example, on a lawn make sure you use all like popup sprinklers with the same flow and throw rates.
• Keep your lawns and garden zones separate.

The five main sprinkler groups are: 

• Garden micro sprinklers.
• Static (non-rotating) lawn sprinklers.
• Mid-range single jet rotating lawn sprinklers.
• Mid-range multi-jet rotating lawn sprinklers (not included in this website).
• Longer range single jet rotating lawn sprinklers.

Most lawn and garden sprinkler systems can be set up using 19mm low density poly pipe, which can be purchased in a large role. This type of pipe is easily joined using poly clamps and poly joiners such as 90 degree elbows. It is easily trimmed to size, laid in place, connected and terminated making it an extremely DIY friendly exercise.

The best solution for your home

With so many options and installation quick, simple and straight forward you will want to incorporate irrigation into your next garden project. But what sprinkler is best for your situation?

Please refer to the table below for a quick reference guide:

Lawns

 

Gardens

Match the different plant groups in your garden to different watering methods.

• Use Drippers for shrubs and ground cover.
• Use Micro Sprays for flower beds, garden beds, shrubs and ground cover.
• Use Drippers or Misters for pots and hanging baskets.
• Use Pop-Up Sprinklers in your lawn.

For more great information on garden and lawn irrigation please download this handy Irrigation Planner from Neta. Neta are one of the leaders in garden watering solutions and Centenary Landscaping Supplies a whole host of their irrigation products.