Is Drip Irrigation?
Drip Irrigation System Design and Components
Resources - drip irrigation
Wisely - for more information on water conservation
in the home landscape.
Drip irrigation is an efficient and economical method of watering. Used commonly
in dry regions with scarce water resources, the use of drip irrigation
is increasing in the Northeast. This irrigation method is typically more
than 90% efficient
at allowing plants to use the water applied. Unlike other forms of irrigation,
such as sprinklers that are only 65-75% efficient, drip irrigation reduces
runoff and evaporation. Drip
irrigation applies the water slowly at the plant root
zone where it is needed.
irrigation has more commonly been used in commercial nursery
and agricultural operations, however, homeowners
are beginning to take advantage of its uses
and benefits. As a homeowner, you can use drip irrigation in your vegetable
gardens, and to water trees and shrubs. You can see current examples of drip
irrigation at the URI Cooperative Extension Master Gardener
Demonstration Vegetable Garden located at URI
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Drip Irrigation Benefits
Drip irrigation involves placing tubing with emitters on the ground along side
the plants. The emitters slowly drip water into the soil at the root zone.
Because moisture levels are kept at an optimal range, plant productivity
and quality improve. In addition, drip irrigation:
Prevents disease by minimizing water contact with the leaves, stems,
and fruit of plants.
Allows the rows between plants to remain dry, improving access and reducing
Saves time, money, and water because the system is so efficient.
Increases effectiveness on uneven ground.
Reduces leaching of water and nutrients below the root zone.
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Drip Irrigation System Design and Components
The main components of a drip irrigation system include the mainline, valve,
sub-main, backflow preventer, pressure regulator, filter, tubing adapters
and fittings, drip tubing, emitters, and end caps. The mainline is the
pipe that runs from the water source – typically your outdoor
faucet - to the valve; and the sub-main runs from the valve to the
point where the drip
tubing is connected. Generally, sub-mains are used only when there are
multiple lines of drip tubing and zones feeding off of the same mainline
The combined length of the mainline and sub-main should not exceed 400
valve controls water flow into the system and can be set
for either automatic
or manual control.
Backflow preventers are necessary to ensure that irrigation
water does not flow back into the pipes and contaminate your main water
Pressure regulators are only necessary if your water pressure
is over 40
pounds per square inch. If you do not know your water pressure it is
a good idea to install one just in case.
Filters keep dissolved substances in your water from clogging the
emitters over time. Install filters either at the emitters or at
the water source to
protect both the valve and pressure regulator in addition to the emitters.
It is best if the filter has at least a 150 mesh screen or higher.
adapters and fittings are used to attach the drip tubing to the rest
of the system.
It is important that these are the right size for the tubing to prevent
them from blowing apart under pressure.
Drip Tubing and Emitters
Drip tubing is a polyethylene tube with emitters placed along the plants. The
emitters release the water from the drip tubing. Drip tubing and emitters
come in various types and diameters depending on your needs. The length of
a single drip tube should not exceed 200 feet from the point where water
enters the tube. You will need to stake the tubing to keep it from moving.
As a rule, don’t bury the drip tubing and emitters, even if they are
designed to be. This helps to prevent clogging and rodent damage.
Emitter Spacing and Design
Emitters can be spaced evenly for row crops, and this design is known as an
emitter hose. Emitters can also be spaced intermittently for plants spaced
further apart, such as trees, shrubs and perennials. With an emitter hose,
the emitters will generally be spaced about 18 inches apart. When watering
trees and shrubs, there should generally be two emitters per plant. Emitters
typically have a flow rate of 1 gallon per hour, though a flow rate of ½ gallon
per hour may be better for maximum efficiency. The end cap is placed at the
end of the drip tubing to prevent water running out the end.
Basic Operation and Maintenance
Drip irrigation can be set to run automatically, like sprinklers, or controlled
manually. Manual operation allows you to take advantage of rainfall before
applying unnecessary water. For more information on proper watering, view
our Water Wisely factsheet.
small amounts of water are applied slowly, drip irrigation
is designed to run daily unless it rains. How long to run
the drip irrigation system will
depend on how much water your plants require per day and the flow rate of
your emitters. Water is applied either once or twice a
day. Early morning is the
best time to water because there will be less evaporation. Watering in the
evening increases the plant’s susceptibility to disease.
filters and emitters on a regular basis to ensure they
are functioning properly and not clogged. To
prevent winter damage, take up the drip irrigation system
at the end of each gardening season.
Most suppliers/manufacturers of drip irrigation systems will provide specific
design, installation, operation, and maintenance specifications and guidelines
that should be carefully followed.
The cost of a drip irrigation system will vary depending on the
size of the area to be irrigated and the type of emitters and tubing
of the size of the area being irrigated there is an initial upfront
cost for standard items such as the valve, pressure regulator,
preventer. Typically, a drip system for a home garden area will
cost between $200 and
$600. For example, the drip irrigation system
installed (July 2004) at the Demonstration Vegetable Garden located
East Farm irrigates 4,300 square
feet in three separately controlled zones, and cost about $500
hose is another irrigation alternative. Soaker hose
requires less equipment and is easier and cheaper to
install than drip irrigation. A soaker
hose is a porous hose that can be connected to an outside faucet, garden
hose, or rain barrel and laid out along the base of the plants. The hose
allows water to slowly seep out along its length. This system works well
with plants that are close together, such as ornamental beds with clumped
flowers or groundcovers.
However, a soaker hose should not be used to irrigate plants,
trees, or shrubs that are spaced
the area in between the
plants will be unnecessarily watered.
Drip Irrigation Design Guidelines. Jess Stryker. http://www.irrigationtutorials.com/dripguide.htm
Introduction to Drip Irrigation. Clinton C. Shock. Malheur Experiment
Station. Oregon State University. http://www.cropinfo.net/drip.htm
Drip Irrigation for Home Gardens. I. Broner. Colorado State
University Cooperative Extension. http://www.ext.colostate.edu/pubs/garden/04702.html
CE Master Gardener Demonstration
Vegetable Garden -
view close-ups of drip irrigation components. View additional
examples at URI
our fact sheet water wisely for additional information
on water conservation in the home landscape.
Books on Drip Irrigation
Drip Irrigation for Every Landscape and All Climates: Helping
Your Garden Flourish, While Conserving Water! Robert Kourik
and Heidi Schmidt. 1993. Metamorphous Press.
All About Sprinklers and Drip Systems. Ortho Books. 1998.
Garden Watering Systems. Susan Lang. Sunset Books. 1999.
Watering Systems for Lawn and Garden: A Do-It-Yourself
Guide. R. Dodge Woodson. Storey Books. 1996.