Drip Irrigation
Drip or spray... which is really better for my yard?
Of course there is no panacea, no one "right answer". It all depends on your particular watering situation. Let's take a look at how drip irrigation and conventional sprinkler systems compare:
| Drip Irrigation | Sprinklers |
| Lower materials costs. | Higher initial materials costs. |
| Easier to install, modify and repair. | More work, and disruptive to the landscape to modify. |
| Frequent monitoring and maintenance. "Hard water" mineral content can be problematic. | More durable components. Infrequent maintenance and repairs. |
| Less run-off, water applied slowly at root zone. | Quicker run-off, more potential for water wasted. |
| Longer run times usually necessary for thorough watering. | Shorter run times per station, more stations watered in a limited time period. |
| Better for deeper rooted trees and shrubs. Good for container plants. | Better for shallow, spreading roots: annuals, many kinds of ground cover and perennials. |
"Drip irrigation" is often a term used to mean a lot more...
It can describe a few different ways of applying water at lower flow and pressure than conventional sprinklers. Other terms sometimes used include "low volume" and "micro irrigation."
Rain Bird uses their own trademarked word: Xerigation (borrowed from a generic term for modern drought-tolerant landscaping, Xeriscape, using "xeri" from the Greek, meaning "dry")
Drip irrigation is water applied to the root zone using a variety of devices first pioneered in agriculture and later adapted for landscape use. These included emitters, soaker lines, and even micro-spray heads.
Drip irrigation tends to apply water more efficiently, but is often more subject to damage from shovels, rakes, and occasional squirrels and other rodents because it is installed at or just below the surface of the ground.
Drip also requires a maintenance commitment. Filters need to be cleaned regularly and emitters need to be checked and occasionally replaced.
True drip irrigation is most useful for shrubs, trees and container plants. " Micro-sprays" are a hybrid between drip and spray heads, and an option for dense ground cover and shallow rooted annuals and perennials.
Essential components of a drip irrigation system:
Filters
Because water is applied via small holes, good drip filtration is an absolute must!
Sand, grit, rust from old galvanized pipes, and mineral deposits from hard water can all contribute to clogging.
I prefer 150 to 200 mesh stainless steel screen in-line filters. Filters should be checked and cleaned at the beginning of the watering season, and again during the warmer months when watering is more frequent.
Pressure regulators
Fixed regulators are installed after individual valves and are more economical where one drip valve is isolated, or in a group with other sprinkler valves. Generally they only reduce pressure by a factor of three, i.e., 90 PSI reduced to 30 PSI.
Adjustable regulators are useful for mainlines under constant pressure. They are more economical in situations where several drip irrigation valves are grouped together.
Drip irrigation works best below 50 PSI, therefore if your unregulated water pressure exceeds 90 PSI, an adjustable filter with a range of 25 PSI to 125 PSI and an incoming pressure capacity of at least 150 PSI is recommended.
Tubing
Drip irrigation most often uses flexible black polyethylene and vinyl tubing with compression fittings, which require no glues or solvents. Emitters and other watering devices have barbed ends which insert into small holes pierced in the tubing.
In most instances, tubing is installed at ground level and covered with mulch.
I prefer not to use 1/8" tubing, and limit our use of 1/4" tubing, attaching emitters directly to 1/2" tubing wherever possible. In myexperience, narrower tubing becomes something of a maintenance headache, easily cut and overlooked while pruning, and often getting tangled in rakes or sliced with shovels.
Emitters
A wide assortment is available- some self-flushing, some pressure-compensating (best for slopes), some using diaphragms, some using "turbulent flow"- all of them attempting to achieve even water distribution. Emitters come as either single or multiple-outlet styles.
Some systems (such as Agrifim's Duraflo Dripperline) actually incorporate emitters within the tubing, spaced at 12, 24 or 36 inches. These are especially useful for long hedges, shrubs on a slope, stands of trees, or outlying areas.
Call us for more info about drip irrigation and how we can make it work for you.
