How to Irrigate a Lawn

Important guides to assist you in setting up your lawn irrigation. We will be referring to these guides throughout.

The best practice for irrigating a lawn:

Use landscape pop-up sprinklers.
Rotator nozzles attach to the pop-up bodies and give you even and efficient coverage
For larger areas: use the Gear Rotor sprinklers, e.g PGP Ultra.

We prefer pop-ups over drip irrigation because:

Drip irrigation is effective but can make it difficult to detect faults and make repairs.
Pop-up sprinklers are easier to maintain and troubleshoot.

Measure the Area

The first thing to do is to measure your area that you would like irrigated.

This can be a quick drawing with pen and paper or a printed google maps image but it MUST be to scale

Make sure to have your water source/taps shown and any objects that may obscure the irrigation, decks, sheds, veggie garden etc.

I have created an example plan for us to work through together.

Figure out how much water is available

Bucket Test: A cost-effective method to estimate water availability (not 100% accurate).
Flow Meter: More precise but can be expensive.

We avoid inaccurate bucket tests by using around 50% of what the total is. If the test gives you 20L/min, you will spec your irrigation to 10 L/min.

(60 / Time) x Litres

Let us say you filled your 10-litre bucket in 15 seconds.

Time = 15 (in seconds)
Litres = 10
So through the equation,

(60/15) x10 = 40

40 L/mn is the total estimate. therefore we will work off of 20 L/pm

Place the Sprinklers

Using the technical sheets below for Rain Bird and Hunter, you can now start positioning your sprinklers on your layout. These sheets provide details on the distance and L/min flow rate for each nozzle arc.

Steps to Follow:
Mark Placement: Place markers on your plan where you believe the sprinklers should be positioned for optimal coverage.
Aim for Head-to-Head Coverage: Ensure that the sprinklers are spaced to provide consistent, overlapping coverage across the lawn.
Avoid Obstacles: Make sure the water is not sprayed onto areas like the house, concrete paths, or any other non-grassy surfaces. Imagine there's a fence surrounding the lawn, and avoid spraying outside that boundary.

For the example plan, I have used the Rain Bird R-Van Rotators and placed them where I think I can get good coverage. For educational purposes, I have added the spray areas to try and demonstrate the water coverage. Try to get as much of the lawn consistently covered as we can without throwing into the house, paths or fences. You can't be perfect with every lawn area, but the aim is to try and cover the lawn consistently and completely.

For the example below, I have removed some sprinklers from the plan to show the comparison. You can see dry patches throughout the lawn, with grass that would end up dying, leaving a patchy, ugly lawn.

A common question we get is, why so many sprinklers? Can't I just put a strip down the middle doing the whole lawn? Below you can see the disadvantage to doing that. You may save money, but your lawn will die, you'll waste water throwing into the house or on the path (if you have iron in your water, this will stain), and you'll end up having to fix the mistake later.

Zone the Sprinklers

Here is where it gets tricky, so if you are having troubles, call our experts on 0800 130 905

In this example, we have given ourselves 20 L/min of water to irrigate the lawn. Each sprinkler requires a certain amount of water to operate optimally. You can see this in the Tech Sheets above.

We have in our plan

17 x R-Van 14 - 90 Degree
20 x R-Van 14 - 180 Degree
1 x R-Van 14 - 270 Degree
5 x R-Van 18 - 90 Degree
5 x R-Van 18 - 180 Degree
5 x R-Van 24 - 90 Degree
2 x R-Van 24 - 180 Degree
1 x R-Van 24 - 360 Degree

R-Van 14

17 Nozzles x 1.06 L/min = 18.02 L/min
20 Nozzles x 2.12 L/min = 42.40 L/min
1 Nozzle x 3.18 L/min = 3.18 L/min

R-Van 18

5 Nozzles x 1.89 L/min = 9.45 L/min
5 Nozzles x 3.82 L/min = 19.1 L/min

R-Van 24

5 Nozzles x 2.46 L/min = 12.3 L/min
2 Nozzles x 4.92 L/min = 9.84 L/min
1 Nozzle x 9.54 L/min = 9.54 L/min

Total Water usage for all the sprinklers is 123.83 L/min
We may need to split the sprinklers into seven zones to get under the 20 L/min limit.

Let's break it down to make it easier to understand and work on the front lawn, as seen below.

Tip: It's best to use the nozzle's open flow when calculating, even when not throwing that Radius. It is normally bolded in the tech sheet.

Front Lawn

3 x R-Van 18 - 90 Degree @ 5m radius = 5.34 L/min
3 x R-Van 18 - 180 Degree @ 5m radius = 10.32 L/min
6 x R-Van 14 - 90 Degree @ 4m radius = 6.36 L/min
2 x R-Van 14 - 180 Degree @ 4m radius = 4.24 L/min

Total = 26.26 L/min

2 Zones are required as we can't run all the sprinklers at once with our 20 L/min. Think of where the pipe will go and what work easiest for you.

Zone 1 Nozzles (Red)

2 x R-Van 18 - 90 Degree @ 5m radius = 3.56 L/min
2 x R-Van 18 - 180 Degree @ 5m radius = 6.88 L/min
1 x R-Van 14 - 90 Degree @ 4m radius = 1.06 L/min
1 x R-Van 14 - 180 Degree @ 4m radius = 2.12 L/min

Total = 13.62 L/min

Zone 2 Nozzles (Blue)

1 x R-Van 18 - 90 Degree @ 5m radius = 1.78 L/min
1 x R-Van 18 - 180 Degree @ 5m radius = 3.44 L/min
5 x R-Van 14 - 90 Degree @ 4m radius = 5.3 L/min
1 x R-Van 14 - 180 Degree @ 4m radius = 2.12 L/min

Total = 12.64 L/min

Our sprinkler will now work within our range, provide room in case of spikes or shortages. I choose these zones to have the pipes not cross the middle of the lawns and keep the trenches straight lines. We would have to dig under the path to connect the sprinklers, so it was easier to zone the sprinklers close by in one zone.