21-day lockdown – Day 18 – Creating a robust irrigation system – Part 2


21-day lockdown – Day 18 – Creating a robust irrigation system – Part 2

Last week we discussed one of the fundamentals of creating a robust irrigation system, namely using HDPE pipes and fittings. Today we’d like to extend this article and discuss the other factors that make an irrigation system robust.

As mentioned previously, we want our systems to be as robust as possible, so that they are long lasting and have few maintenance problems. This means the materials we use are of a higher quality than standard DIY materials, and are therefore more expensive. If you want to install your own system, and want to be able to easily adjust it in future, then using LDPE pipes and fittings, or entry-level materials, will make your system a cost-effective DIY project. Otherwise, here are the principles and materials we – and other industry professionals – use in order to create robust irrigation systems:

  • HDPE pipe and fittings
    Read our article on this here
  • Trenching to 400mm (or more)
    Where possible, irrigation trenches should be dug to 400mm or more. This ensures that irrigation pipes are kept well away from general gardening tools, such as spades and forks, which could potentially puncture them.
  • Place all your pipes and cables in one trench
    Where possible, it’s worth placing all your pipes and cables in one trench, including your main water lines, electrical cables for garden lighting, fibre, pool pipes, and even drainage pipes. We often make changes to the layout of pipes and cables in our client’s gardens, because it makes it much easier to know where all their piping is in the garden in future. Placing danger tape over the pipes is also good practice, and will help to warn someone working in your garden that there are pipes beneath it. Afterwards, providing a CAD design showing the layout of the cables and pipework is beneficial for the home owner.
    irrigation design
  • Use swing-joints or flex-pipe for the pipe-to-sprinkler connections
    One of the reasons people don’t trench their pipework deep enough is because they connect their popups directly to the pipes. This might be fine for a small DIY project, but it creates maintenance problems in larger installations, because the pipes are no longer trenched deep enough, and any work by a gardener risks puncturing them. Professional irrigation installers trench their pipes to 400mm or more, and then use swing-joints or flex-pipe to connect the popups to the pipework. This has multiple advantages, including being able to easily adjust the position of the popup in future if it shifts position or angle – something that is difficult to correct if the popup is connected directly to the pipe. Some installers, ourselves included, take this a step further and also connect risers to swing-joints, again for flexibility in adjusting them in future. Additionally, if the riser is ever damaged (e.g. by a car, a dog, or kids playing with it), then the main pipework is not damaged, only the riser or connecting swing-joint pieces.
  • Quality cabling and conduit
    ‘Comms’ cables, such as these used on the controller above, can void your controller warranty

    The ‘comms’ cables replaced with 1.00mm GP wire

    Irrigation cables (the cables running from your valves to the controller) should be a minimum of 1.00mmGP wire, and should be placed in conduit. Many systems use low-grade cables (often called comms cables), and whilst these initially work, they can easily be damaged, making them difficult to repair. They are also not endorsed by controller manufacturers, who can void warranties if such cables have been used with their controller – we’ve had to replace a number of controllers because of this. So if you’re installing a new system, avoid the temptation to use cheap cabling. Additionally, cables should be placed in conduit to protect them, and also to make it easier to pull through new cables if you ever need to in future. LDPE pipe can be used as conduit, and is the industry standard, but you could also use 20mm or 25mm PVC, which would make it easier to know that this is cabling, and not a water pipe if you are doing maintenance in the garden. We’ve had a few instances where we thought we hit an irrigation pipe, only to start cutting into it (to repair it) and finding that it was actually cables! PVC is also stronger than LDPE, so you’re less likely to have a problem with tree roots crimping the conduit, which would limit the ability to pull new cables through if you ever need to.

  • Follow best practices when setting up your manifold
    An irrigation manifold is the pipework that feeds your irrigation valves. Professional installations use isolation valves, as well as pressure reducers where necessary. Additionally, the various parts of the system that might need to be accessed – such as the isolation valves themselves – should be easily accessible in an irrigation box – there’s nothing worse than an isolation valve that is under a foot of soil!
  • Avoid using micros
    Micro emitters have their place, and are useful in difficult to reach areas, such as planter boxes. But if you want a robust irrigation system, avoid using them in the garden, as they are easily moved by pets, birds, or even foliage growth. Additionally the micro pipes and fittings can become brittle over time, or blocked by plants or grit. So unless you have to use micros, rather use risers, or a dripline if you are irrigating small/narrow areas.
  • Use quality products and brands
    This goes without saying, but it’s worth investing in quality products. There are a number of well know irrigation brands, and using their products will help make your system more reliable and robust. We’re sure new brands will come into the market in future, but for now, it’s worth using the tried and trusted ones in the industry.
  • Use a quality controller
    In a similar vein to the previous point, it’s worth investing in a quality irrigation controller, from a reputable irrigation manufacturer. These controllers have been tested in multiple setups worldwide, and are constantly refined to ensure reliability, accuracy, and ease of use. Every contractor has his or her favourite (Hunter, Rainbird, and Weathermatic are some well-known brands), but so long as you are using one of the reputable brands you are less likely to have maintenance problems with your system. Additionally, it’s worth investing in a controller that is independent from the valve, as opposed to those that are combined irrigation/valve setups (usually those that connect directly to a tap). All controllers are costly, so you want to avoid having to replace the entire controller just because your valve failed, or vice-versa. New valves cost between R200 – R500, whilst new controllers can be up to ten times that price.