By far the most efficient form of irrigation is drip irrigation. This is because water can be applied exactly where it is needed without any worry of it being blown away by the wind, or of it falling in places where it is really not needed, for example garden paths, and running off as a wasted commodity. Micro-sprinkler systems are closely related to drip systems and use much of the same equipment with the exception of the final part of delivery, where the one uses an emitter and the other a micro sprinkler head. Micro sprinklers are another good way of saving water as the sprinkler heads are both nearer to the ground and can be directed very precisely where needed.
The main delivery hose in a drip system is normally a ½" black PVC pipe. When planning the system you should start by measuring out exactly where you are going to place the delivery hose – plan for 90º turns and joins as the PVC pipe is fairly stiff, and does not easily form a curve. Joints in the pipe are made with either elbows, T-pieces or straight joins. The ends of the pipes are normally sealed with end pieces, but can also be folded back on themselves and tied with wire.
Emitters or micro sprinkler heads are connected to the main delivery pipe via a ¼" PVC pipe and a double ended barb. A hole is made in the ½" pipe with an awl and the barb forced into the awl and into the end of the ¼" pipe. These PVC pipes can sometimes be quite difficult to work with as they are quite hard – it helps to have a jug of near boiling water in which to soak the pipes, thus making them softer and far easier to work with.
Drip systems are very versatile and can be used on either a large or a small scale. Ideal water pressure is about 25psi. 15psi is too small a pressure and with anything above 30psi you will need to purchase a pressure reduction valve. It may be useful to include a filter in the main delivery pipe if the water supply is suspected of having any small solid contamination. The holes used in the drip and micro spray system are very small and easily become blocked by a small piece of grit or stick. Before Winter sets in remove the end caps and let any residual water drain away – this will prevent any damage being incurred by water freezing in the pipes. Pipes should be flushed out with clean water at the end of Winter and the end caps replaced.
© Michael J Mason 2009