House and Garden

3 July 2012
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Watering the Garden

Many homes in Australia have automated watering systems for their gardens - commonly called 'reticulation' (which means 'network' as in the network of pipes involved), also referred to as 'irrigation' and 'sprinkler' systems.

The systems can be fed from mains water or a bore. How often you are allowed to use your reticulation depends on the season and how drought-affected your region is; currently in Perth there is a total ban through the winter and for the rest of the year you can water on two days per week.

A typical, fully-automated system comprises a network of plastic pipes that run underground from the mains, extending throughout the garden. They are divided into a number of circuits or stations (usually 6 or 8). Each circuit has a number of sprinklers of various types, according to the sort of plants that are being watered. Each circuit has a valve so it can be turned on and off independently. When the valve is on (open), water flows through that circuit and the sprinklers come on. The whole thing is controlled by an electronic controller box, which sends low-voltage electricity to each circuit in turn, opening valves for a set period of time.

The Controller

A fully automated system uses an electronic controller to send low-voltage current to each valve in sequence, thereby opening that valve and running that station for a set time period.

A maximum 20 minutes per station is recomemended in summer and only 10 minutes may be required through most of autumn or spring.

The Valves

The valves use a solenoid mechanism to open; as long as a voltage is applied to them, they stay open and when the voltage is removed a spring returns them to the Off/Closed position.

The valves are usually located underground - they may have a plastic cover so they can be accessed, or may be buried in soil. In older properties, the owners may have no idea where they are and they can be very hard to locate if maintenance is ever required.

Note that a live electrical wire runs from the controller box to each valve, normally taped to the PVC water pipe going to the valve. A neutral electrical wire is also required by each valve, but this can be shared between two or more.

The Sprinklers

Many types of sprinklers exist and range in price from a few cents to $20 or more. Lawn sprinklers are mostly below ground, to allow for mowing and they pop up when they're on.

Garden beds may have sprayers covering an area of a few square meters, or mini sprayers or drippers to each plant.

Routine Maintenance

The following routine maintenance usually applies for home owners AND tenants of rentals:
  • Set the controller to run for the correct number of minutes on the correct days. Also a good idea to switch the system off altogether if there has been rain.
  • Check for blockages to sprinklers. The first indication is normally that some plants start dying! Sprinklers can get blocked with a single grain of sand and can be unblocked with a pin or just by disconnecting and giving the sprinkler a shake.

Other Maintenance

More serious problems would not normally be the responsibility of a tenant. While reticulation is well within the capabilities of most handy home-owners, they may want to call in an expert. The kind of problems that occur are
  • Broken pipes. I would think most home owners will put a spade through a retic pipe at least once. They can be repaired with some replacement pipe, couplings and PVC pipe cement.
  • Pop-up sprinklers. Lawn sprinklers get broken by cars driving over them, or they just degrade over time, or get blocked up with sand so they don't pop up any more. Usually, you just replace them, but it takes a bit of digging and fiddling about.
  • Valves. If a valve stops working, it could be because the electrical wire is broken, or the solenoid has stopped functioning or the valve is blocked mechanically, or the controller is not actually sending a voltage. So, plenty of things to check and it may be a big job just to find the valve. Be patient!!
  • Controller. If the controller stops working, you can check the fuse (they normally have about a 1 amp fuse) and maybe check the low-voltage connections, but after that it is probably one for the experts.