|
Check
this out:
Gregg
was interviewed for an article in the June 2008 issue of
Irrigation and Green Industry,
Low Volume Irrigation Comes Into
Its Own.
Drip
irrigation or sprinklers... 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 groundcovers 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."
Rainbird 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 groundcover and shallow
rooted annuals and perennials.
The keys to effective drip irrigation are
good filtration and pressure
regulation.
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.
We prefer 150 to 200 mesh stainless steel or nylon
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
There are two kinds of pressure regulators, fixed (or
pre-set) and adjustable.
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 at or below 30 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.
We 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 our experience, 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.
Emitters photo courtesy Rain Bird®
Call us to learn more about drip irrigation and
whether it will work for you.
408.369.1391 | 
