For almost three years (the whole time we’ve been here), we’ve been using passive water harvesting, hand watering and using sprinklers strategically to irrigate our growing garden. However, the plan has always been to install dripline irrigation, as it’s the most water efficient and time saving approach available.
But before we could do that we had to replace some significant water pipes, build a series of retaining walls (which pipes had to be integrated into), build some steps (which some other pipes had to be integrated into) and upgrade another mains water line. This took a while. So it was only a couple of months ago we finally got to install our driplines, suffice to say we love them. Here’s an overview of how to do it so you too can be liberated from hand watering.
Before you start *anything*, the first process to go through is the design stage. Map out your garden and measure the areas you need to irrigate. From here, you can create an accurate shopping list and be super efficient with resources and time – a big theme for us.
But before you can start shopping, some basic information…
What is dripline? – well, it’s a line of plastic tubing that drips. There are a range of variations, with soaker hoze, leaky pipe and 13mm poly pipe with drippers that you punch into them at desired intervals. However we have been eyeing off dripline with the drippers pre-installed in the line. With products such as Toro and Netafim being popular brands – in terms of budget and quality, these seem to be some of the best. The Toro pipe we’ve used has drippers every 300mm (one foot in the old scale) – each dripper releases 2 litres of water per hour.
How does it work? The drippers drip onto the soil, from the place the water hits the soil it spreads in a cone shape. With sandy soil the drip is a very narrow cone, pretty much just wetting the soil immediately below the dripper. With clay soils the cone has a very wide angle, effectively watering a larger area. As a result, the spacing using drippers will change depending on your soil type.
Pressure compensating Vs Non Pressure compensating drippers? If you are buying dripline you will come up against this terminology. Basically pressure compensating drippers can work over a range of water pressures. Why does this matter? Hilly and steep sites create different levels of water pressure. Thus using non-pressure compensating drippers could result in the bottom of the hill getting more water than the top. I have heard it recommended to use the pressure compensating drippers if the irrigation slope is over 2 meters or if the runs of dripline are very long. There is a whole science to this and this site has a great overview of the topic. Given our steep slope, we used pressure compensating drippers.
Calculating the dripline length: First we measured the bed length and width. Then calculated the number of driplines per bed. We have spaced our drippers around 300mm apart, from this you can calculate the length of dripline you need.
Draw a map of how it will work on the ground. From this you can calculate all the T connectors, elbows, 13mm plain line, clips, ends and valves you will need. Once you have worked out how many you will need, add another 20% to these. Plans change and having them on hand lets you adapt and change the design as your garden evolves.
Buy the bits. Word of caution, avoid the mainstream, heavily over priced hardware stores. Go to an irrigation specialist in the “industrial” part of town. In Hobart we use Hollander Imports or Irrigation Tasmania. If you are buying online these people have very good prices and products.
Each section of our garden is watered by a manual tap which is in turn directed to 3 or 4 sub sections of the garden. In this way we can water fruit trees differently to our vegetables as their water needs are drastically different. To do this, we create a “manifold” using a variety of connectors – the image below shows the items required.
Prepare the connectors in plain 13mm poly pipe. You can use pliers or the tool below – a razer blade with leverage, affectionately known as the finger cutter.
An incredibly helpful tip is have some hot (almost boiling) water on hand to place the pipe in, this helps the pipe stretch to attach each piece together easily. We fill a thermos of hot water and pour it into a cup as needed – this little trick will save you a lot of time and frustration.
Attach the bits together to test it will fit the area it is made for (always test first).
Clip the fittings together and attach in place.
So we could still use each tap we installed a tap splitter, make sure you use plenty of plumbers tape so the tap fittings don’t leak.
The dripline is attached to the tap using a standard hose tap fitting, simply put the poly pipe in hot water then attach the tap fitting – too easy.
Next we need to lay out the driplines for the beds, you can see in the bed below we have set four driplines in total.
At the manifold/tap end of the driplines, we have created another set of T’s and elbows that distributes the water into each dripline. This is measured out so that the driplines are in the correct position on each bed.
Once all of the above is clipped together we run water through the system. This is to flush any dirt or plastic scrap that may be in the pipe. Once this is done, we put the ‘end caps’ in place to block the end of the pipe – alternatively you can put valves at the end so you can flush the system in the future.
Because we’re often working vegetable beds where we do seasonal mulching/planting/digging we had to make sure the irrigation is easy to move. To do this, we attached one end to a timber strip at the end of the bed so we can just pick the whole thing up together. You don’t have to do this, indeed,for some contexts it might be easier to have them loose and just pick them up one by one.
Oh, and if you run out of connectors or don’t like chopping the pipe up, you can always put it down in a spiral. Just know that if you have seeds or young seedlings you’ll need to do a bit of hand watering to make sure they get enough water in the early days.
So that’s the basics of our dripline system. We have spent around $500 and have around 1/2 of our 1/4 acre block under dripline now. We think it’s more than worth it as It’s a great time saver.
And if we where to do this again? We would think a bit harder about the original main water pipe layout (a 20mm blue line poly pipe). We would duplicate the system so there was a “dripper” dedicated pipe and a “tap” dedicated pipe. That would mean we could then just turn one valve and water the whole garden. This would be specifically for when we go away and we get our awesome neighbours to water the garden…. And of course you can put an automatic timer on some/all of your irrigation system – we haven’t gone there yet but it is a consideration in the future. We see what we’ve done now as an awesome stage one that fits within our context and capacity.