Irrigation Systems and Installation
by Ruth Foster
Have you had it hauling hoses around
to cope with drought? Maybe
you think it's time for a sprinkler system, especially for your precious
green lawn. If you have some
cash to spare it may not be such a bad idea.
However, be forewarned.
Sprinklers are not simple and if poorly designed or badly
installed, they will become a permanent maintenance pain.
The two basic types are surface drip systems or underground systems.
SURFACE DRIP SYSTEMS are the
cheapest and easiest to install. They're most useful for shrub beds,
vegetables, or flower borders and may also be connected to big planters.
The easiest is 'Leaky Hose' which is
just that, a hose that leaks all along its length.
You turn it on and when you think it's enough, you turn it off. Problems are that it's hard to calibrate, it becomes brittle
after cold weather and sometimes clogs with fungus.
More sophisticated drip systems use
sturdy plastic tubing to which thin tubes and emitters are attached by
punching holes in the plastic tubing.
The emitters are sized according to the size of the plant or shrub
and its water need. A small
plant may have one emitter, a tree may have several. Unneeded holes may be
closed and new emitters may be added.
Large systems are often individually
designed by the irrigation company which supplies the parts.
These include the tubing, emitters, a line water pressure adjuster,
an automatic timer, connectors and T-joints.
Drip systems deliver water directly
to the soil around each plant and therefore use water more efficiently
than overhead sprays which lose water to evaporation, especially in dry
climates. And water can be very expensive.
Surface drip systems are most useful
in southern climates that don't have frosts (which may burst the tubing),
and they're shorter lived than underground installations.
Breaks in the tubing have to be mended as needed, and in cold
climates, the systems have to be blown out with compressed
air before winter.
UNDERGROUND SPRINKLERS are what most
people are familiar with, especially for the lawn.
They’re usually installed by sprinkler companies. In addition to
the reputation and experience of the company, there are some additional
things to check out before you sign a contract.
Most important is the design. It involves an analysis of your water pressure,
choosing the right components,
keeping beds and lawn zones separate, and providing zone-to-zone coverage
but without wasting water. Experienced
installers can do it quickly, but be sure to ask a lot of questions.
Check the quality of the parts. Most contractors don't use only one supplier, but might buy
the controller from Rainbird, the pop-up heads from Hunter and the valves
from Weathermatic. How long
is the guarantee period? Winters
can be hard on sprinklers.
Ask about the controller.
Prices range from $80 to $400 and you get what you pay for.
A good one should be able to set different zones for different
schedules per week. There
must be manual override so you can
turn parts off and on when you wish.
There should also be a rain sensor to conserve water and not
irrigate when the ground is wet.
If you know plumbing and are handy,
you can buy homeowner do-it-yourself kits.
However designing it is complicated, the parts are stiff and tricky
to put together plus there's a lot of digging involved, but you can save
50% of the cost.
The biggest problem is if they are
not installed deep enough, especially the do-it-yourself systems.
If too shallow they can be punctured with an edger or lawn aerator.
Frost heaves can push pipes to the surface which may trip someone
or be damaged by the lawn mower. Six
inches deep is a minimum, eight is better.
Most systems need professional maintenance in fall and spring, and
in northern climates they have to be blown out before frost.
A serious mistake is to adopt a
watering schedule for golf putting greens in Arizona (a little each
morning). Such short, frequent watering encourages shallow rooting,
disease and lower resistance to drought
and heat. Instead, water less
often, once or twice a week, and wet the soil 6 or 8 inches deep,
especially for northern lawns and newly planted trees and shrubs.