Garden irrigation system

[GardenerJohn]

Hi,

Great video on setting up an irrigation system - but what was the point of the water pressure test?

The video showed how to do one, but not what to do with the results? I'm sure it's important for some reason?

Grateful for your advice.

Thanks

Gardener John

[Jason]

Hi @GardenerJohn,

Welcome to Workshop. We're pleased you could join us. I trust you will find our community members are the source of a lot of helpful information and inspiration for your projects.  

A garden irrigation system is certainly a great project coming into the warmer months. I'm sure community members like @Branchy249 or team members at your local Bunnings store will be able to assist you with suitable products for your system once you've worked out your maximum flow rate. Have you already done the test?

For the benefit of other members, I believe John is referring to the Bunnings video below, which is part of a four-part series on installing an irrigation system. 

Thanks again for joining in the discussion,

Jason

[Branchy249]

Hi Gardener John,

The pressure test allows you to identify how many pop up sprinklers you can run off your line at any one time. There are a number of different pop up sprinklers that are available and they all require different water pressures to operate effectively. Some are suited to lower pressures, whilst others require higher pressures to operate. This can also determine how big the coverage of the sprinkler is.

If your pressure is too low, you may need to run multiple lines which can easily be done.

[Jason]

Hi @GardenerJohn,

Just checking in to see if you have managed to do that water pressure test as yet?

Jason

[GardenerJohn]

Thanks Branchy, appreciate your time to reply. Yep, get the principle but I'm looking for the implementation.

I'm guessing there is some sort of ratio - tap flow rate divided by pipe distance and width  (5m x 19mm) to determine the number of trickles I can poke into the delivery pipe.

Any thoughts.

Cheers,

GardnerJohn

[DCS]

Gidday GardnerJohn,

To answer your question as simply as I can, the water pressure test is used to determine the amount of sprinkler heads you can use on the one line. There really isn't a ratio so to speak of, but you do have to know the flow rate of the sprinkler heads. Simply, you just add up the flow rates on the sprinklers so that their flow rate is below the maximum flow rate of the tap.

For example: Your tap will flow at 100 litres per hour. That will allow you to run 10 sprinkler heads that have a flow rate of 10 litres per hour, or 20 sprinkler heads with a flow rate of 5 litres per hour.

Of course with you're dealing with drippers, this information is pretty useless because drippers require very little pressure. Some drippers have a fixed flow rate, whereas some are adjustable.

The rise (the amount of height the water has to travel up hill from the tap) and the run (the amount of distance the water has to travel away from the tap). The rise and run is very important if you use pumps to pump your water around your block but if you use town water it isn't really that important if you live in a city residential area as most places have enough pressure to deal with the average size blocks.

It all depends on what you are trying to water... is it a lawn or a garden bed? Because both applications have a different way of setting up to get the most out of your watering system.

I hope that helps.

[Jason]

Thanks for joining the discussion and sharing your expertise @DCS. I'm sure @GardenerJohn appreciates the advice.

Let me also extend a very warm welcome to the Workshop community. It's great to have you join us. I hope that in addition to enjoying sharing your projects and knowledge that you can get plenty of helpful information and inspiration from our community members.

Please let me know if you ever need a hand getting the most from the site, or have any feedback on how we can make Workshop more useful for you.

Jason

[GardenerJohn]

Hi DCS,

Your information helped enormously. Done the calcs and installed the system today - seems to be working well. Small issue, some leaking where the link to the tap joins the irrigation line connection. Point of greatest pressure I guess. I had used a circular plastic clips to lock the irrigation head to the polypipe. I'll replace it with a metal clip, which I should be able to tighten more securely.

Thanks again DCS.

Cheers,

GardnerJohn

[Jason]

Visitors to this very popular discussion at this time of year might also like to check out these other Workshop posts:

• New watering system help

• Holman BTX1 watering controller review

• Watering system

• Garden irrigation system

• Setting up an automatic irrigation system.

Feel free to post if you need a hand with anything. 

Jason

[robchin]

@GardenerJohn - assuming your system is still going well.

I noticed that this conversation has been very popular within the Workshop community. I know this is a bit late - but I've only just seen this one, but I thought I'd share it for others doing the same thing who might need similar advice. It's a small thing but the test being described is a 'flow-rate' test - not a pressure test. As described you do the test to work out how much water you have available and therefore how many sprinklers you can run at once. A pressure test uses a pressure gauge and tells you how much pressure is available to run the sprinklers. In most parts of Australia with mains water you'll have plenty of pressure to run a sprinkler system but your flow rate (how much water comes out of the tap) will be the limiting factor. Always do a flow-rate test before you design your sprinkler system. To get the most accurate result: 

1) Turn the tap on to full then 

2) Put the bucket underneath and then start timing - only stop when the bucket is full

3) Do the test at the time of the day you plan to use the sprinkler system

4) If you are going to use the system with a timer - do the test with the timer on the tap - it will restrict the flow so you want to get a realistic figure

5) Fudge factor - only design for 80% of your calculated capacity. 

One final note - the bigger (diameter) the pipe that you use the better. 19mm minimum for pop-up sprinklers. 

Hope that helps.