After fine grading has been done, the irrigation system goes in the ground. This system happens to use spray heads – but it could have used one or more types of drip irrigation, or a combination of drip and spray or drip and stream rotors.
Systems that shoot water through the air are called broadcast; anything that drips – logically enough – is referred to as a drip system. Some types of drip line can even be buried either under bark or in the soil, depending on soil type. Drip is also considered to be more efficient than broadcast systems, although maintenance can be more difficult since it may be impossible to know if the system is working by watching it, as is the case with underground emitters.
All automatic irrigation systems have these components:
- A backflow prevention device that stops dirty water from the irrigation system from getting sucked into a potable water supply.
- A controller, or “clock” that tells the valves when to water via electrical signals sent through wires
- Remote control valves, controlled by the clock, that open to let water into the drip lines or sprinklers
- A delivery system, either broadcast or drip – or a combination of several systems.
- Pipes, typically Polyvinyl chloride (PVC). This material is not especially Earth-friendly, and other types of plastic are coming on the market. One drawback to PVC is that fumes from the solvent used to join the pieces is not something you want to breathe. Alternate systems typically use compression fittings that hold the pipe securely without any glue or solvent.
- Control wires. Either one common wire (a ground) and one control wire per valve (traditional systems), or only two wires that carry digital signals from the clock to decoders that in turn activate the valves.
- The most important component of any irrigation system is the operator. Although weather-controlled controllers are becoming more and more frequent, a competent person is still needed to oversee the system and ensure that it’s running correctly. A good example was a garden that was being drowned by over watering – someone had bypassed the automatic weather station and manually told the system to water much too frequently, even in the rain!