Irrigation, merits of various water pipe options

[steveof2620]

Hello,

Now I have completed my garden wall, I'd like to install an irrigation system. I am wondering which irrigation piping system would be best. I have used poly-pipe before but I have found it to be brittle and prone to leaks so I am looking for something a bit more ... well, sturdy.

Thinking about:

• Vinidex 25mm blue poly pipe;
• Holman 19mm Black Flex-Tube.

I also have 3 x 3m Holman 20mm pressure pipes as well.

The total length of the run from tap to manifold would be about 15 metres. From there it would split into 3 seperate zones and I'd probable use poly pipe from there. 

Anyone have any advice on which might be the best option?

[robchin · Accepted solution]

Hi @steveof2620 

Good question - if it's carrying mains pressure most of the time you will HAVE to use the PVC pressure pipe or the Vinidex 25mm blue mains pressure poly pipe. Both of these are designed to mains pressure. I reckon the Mains pressure poly may be a bit dearer but is easier and more margin for error. Some states will have regulations about using licensed plumbers in some situations and the need for a Backflow prevention device and shut-off valve. 

Good luck. 

[Jason]

Hi @steveof2620,

Apologies for the slow reply. Let me tag a few experienced members for you who might like to share their thoughts: @Adam_W, @Prawns, @TheSaltyreefer.

Our resident Bunnings D.I.Y. expert @EricL will also be happy to assist as soon as possible. 

Thanks,

Jason

[Adam_W]

Hi @steveof2620 the best system for actual water distribution will be drip-line as it ensures even water distribution & you don't have the wastage that you often get from typical sprinkler heads. 

As @robchin Rob said if you're running straight from mains then you'll likley need a pressure reducer and a backflow prevention fitting is a must.
You may find some useful tips in my video on the subject from a few years back. This is only single-zone system but explains a few different areas.

[steveof2620]

@Adam_W 

Thanks for that. I really, really, really wished I known that yesterday! Is this the line you are talking about?

https://www.bunnings.com.au/vinidex-25mm-x-25m-metric-blue-poly-pipe_p0179109

Are there any guides available as to how to join lengths of this pipe together? What connectors should be used? Are they glued or clamped?

Also could you recommend a suitable 'backflow prevention device' that would be compatible with the pipe and a standard tap? Is this the sort of thing I need?

https://www.bunnings.com.au/kinetic-chrome-backflow-preventer_p4920512

 

[steveof2620]

Thinking of something like this...

[EricL]

Hello @steveof2620

It's great that you've received excellent advice from @Adam_W and @robchin. To answer your first question, you can install a FIX-A-TAP 19mm (3/4") Vacuum Breaker. This will cover your entire setup from the garden tap, but if you wish to install more non-return valves it is possible to do so.

Your reference in your last post is correct. That is a high-pressure rated pipe from Philmac also referred to as a blue line pipe. Here is an example of a Holman 13mm Pressure Reducer And Filter Assembly. It filters and reduces water pressure for your drip feed irrigation system from the mainline. 

There are standard fittings that go from the Philmac fitting system to standard BSP or threaded systems to attach regular plumbing fittings. An example of this is the Philmac 25mm x 1" Metric Poly x MI BSP Pipe End Connector. This connector has a standard one-inch or 25mm fitting at the end of it to link to other fittings, It comes in various sizes and reducers can be used on it. 

Here is a handy link to help you with Philmac installation: Philmac Installation

Here is a handy step-by-step guide: How to install irrigation sprayers and drippers

If you need more advice or information, please let us know.

Eric

[J_Smart]

Such a great video however I have a question on one part.

It suggests making loops in the system. I have always heard of running the system to a dead end.

So would you suggest looping the entire system back on itself near the tap?

[EricL]

Hello @J_Smart

Thank you for sharing your query about the drip irrigation system. Let me tag @Adam_W so that he is made aware of your question. Looking at his example when making loops around midsized plants you need to attach a return line from the last loop back into the mainline. This keeps the water moving and preserves the pressure in your system.

However, if it is a single giant loop system I believe the same principle applies. If you're making your own drip system, please keep us updated. I'm sure our members would love to see the system you're planning.

If you need advice or information about your own drip irrigation system, please let us know.

Eric

[Adam_W]

Hi @J_Smart yes, loops are essential.

Simple reason. If you have a dead-end line the pressure drops for each outlet the further you get away from the tap. To get the last head running at the desired output then you have to crank the system right up. In some circumstances this will result in heads earlier down the line putting out too much water while the last ones barely trickle. Using line with regulated drippers helps solve this as they can't go beyond their set output but they can be damaged by excess pressure.
When you have a closed loop the line will equalise in pressure after a minute or two and the output from each head will be equal (give or take) without having to max out the pressure.
That make sense?