Setting up an irrigation system

Setting up an irrigation system

When it comes to purchasing irrigation systems, you can buy complete DIY irrigation sets or you can design the system and then get the pieces needed.

What was needed in the case of this project was a simple system that would water the garden beds and the lawn without watering the paving. We also wanted to see to it that a birdbath was topped up and small plants in a rockery were watered by the irrigation.

Materials:

• 20mm irrigation pipe: 40m
• Three pop-ups
• Three T-pieces
• One end plug
• Selection of micro jets (spinners, 90° and 180°), supports and 4mm tubing and connectors (for connecting the micro jets to the main pipe)

Note: Materials depend on the extent of the system being installed. Bigger systems will require more piping, sprinklers, etc., and vice versa. This project serves as a guide to the type and number of components you might be considering. The cost of the system you install can range from a few hundred Rand or less up to a couple of thousand or more, depending on the scale.

• In this case, we needed to be able to top up a birdbath and water plants in a rockery. This application called for 4ℓ/hour drip feeders (also available in 8ℓ/hour).
• The pop-ups also needed to be protected from damage from line trimmers, for example. To do this, we included a 1m length of 75mmØ pipe cut into 200mm sections. These were positioned over each pop-up with soil packed around them to keep them in place; they also help prevent soil and plant debris getting too close to the pop-up and possibly causing its operation to be impaired.
• Note that micro jets are available in a range of configurations to suit virtually any application. Spinners provide a 360° arc of coverage, as do some versions without a spinning head. Others are designed to provide spray through a 90° arc, others through an arc of 180°, etc. Chat to the staff in your local Mica’s gardening/irrigation department for advice.
• Tip: keep joins and sharp bends in your irrigation system to a minimum; the more the water can flow through the main 20mm supply pipe and the tubes to the micro jets without impediment and ‘drag’, the more efficient the system will be.
• Make a point of regularly checking and cleaning (and if necessary replacing) the micro jets and pop-up filters; if one or more is blocked or the flow impeded to a pop-up’s nozzle, that will increase the pressure on the rest of the system and that could cause one or more micro-jets to ‘pop out’.
• If using a well-point or borehole, bear in mind that the pump will be rated to a particular power and this will have a bearing on the amount – and pressure – of the water being supplied to the system, so the number of pop-ups and micro jets and nozzle sizes can be something of a juggling act.

Method:

We wanted to make the system as unobtrusive as possible, so the main pipe is buried about 250mm below the soil surface and the only pipes that are visible are those feeding the micro jets on their risers and the end of the pipe where it rises to be connected with the timer.

1. The parts needed for the project. What you need will depend on how big an area you want to cover, the number of pop-ups and/or micro jets you will want and so on, but this all came in at just over R1000.

   

2. One of the pop-ups disassembled. Only the head rotates and the coil spring returns the head to the body of the unit when not in operation, thus keeping it safe and out of the way. Note that when the pop-up operates, it only seals when fully extended, so there can be quite a bit of water shooting up initially until it is fully extended; at that stage, the unit seals itself and all the water is directed out through the nozzle.

   

3. There is a filter at the base of the head unit and it is a good idea to periodically remove it and clean it.

   

4. After cleaning the filter, a little pressure from your thumb…

   

5. …and the filter merely clips back into place.

   

6. Each pop-up is supplied with a range of nozzles of various sizes and depending on the ‘throw’ required, and pressure available, you will be able to select the best option for a particular pop-up. The rotating head has an adjustment screw, which is rotated counter-clockwise for reduced rotation and clockwise for an increase rotation; these are indicated by a minus sign and a plus sign respectively. When adjusting the arc, make very small adjustments, test after each adjustment and adjust again – gently – until the desired rotation arc is achieved.

   

7. The nozzle is pushed into position and held in place with a locking screw. The screw can also serve to adjust the spray pattern – screwing it down more will adjust the nozzle’s angle.

   

8. A small selection of micro jets. The one on the left is a spinner for 360° coverage, the one in the middle provides a spray arc of 90° and the one on the right provides coverage across an arc of 180°, but in a formation of mini-streams.

   

9. We fitted a dripper to one length of tubing so that the birdbath would be topped up.

   

10. A good view of how a 180° micro jet operates. As you can see, no water is directed over the paving.

    

11. A view of one of the pop-ups with its protective shield pipe. The top of the pop-up when it is at rest is actually below the surrounding soil surface while the protective pipe is about 20mm proud of the latter. This ensures that the expensive pop-up is protected, not only when the lawn is being mown or the edges trimmed, but also from bits of grit possibly getting into the mechanism.

    

12. The same pop-up in operation. As you can see, the protective pipe is no impediment to proper operation. If you wish, you could paint the pipe green to blend in better with the lawn. We opted not to.

    

13. When connecting micro jets, allow yourself a bit more tubing than the bare minimum. Yes, it will cost you a few rands extra, but it means you can move the micro jet about a bit, perhaps to give a little more coverage to a particular plant that needs more water.

    

14. If you fit a battery-powered timer like this, you can programme it to provide the irrigation regimen that you require.

    

15. This pop-up has been fitted with a nozzle that provides a good ‘throw’ in large droplets. If you notice that the spray is misting, then switch to a larger nozzle as the larger droplets tend to go where intended whereas a mist spray is blown about all over the place in even the lightest breeze.

    

16. Another 4ℓ/hour dripper, this time fitted on top of the rockery and providing water just where needed whereas a micro jet would result in a lot of wastage.

    

17. The final result. There is some spray over the paving from the directional micro jets in the smaller beds on the left, but the pop-ups on the right are watering the lawn and bed against the boundary wall, without touching the paving at all.

    

An illustration of how the pop-ups arcs were set, and how the protective pipe shield around a pop-up is set proud of the top of the unit, and slightly above soil level, to keep it clear of soil and debris as well as protect it from a careless trimmer or mower.