Drip irrigation is an efficient and economical way to water your yard and garden. Used commonly in drier areas of the country,
drip irrigation is becoming more popular in the Northeast. Unlike other forms of irrigation, such as sprinklers that are only
65-75% efficient, drip irrigation 90% efficient at allowing plants to use the water applied. And, it reduces runoff and
evaporation. Drip irrigation applies the water slowly at the plant root zone where it is needed most.
Drip irrigation has more commonly been used in commercial nursery and farm operations, however, homeowners are beginning to take
advantage of its uses and benefits. As a homeowner, you can use drip irrigation in your vegetable and perennial gardens, and to
water trees and shrubs.
Benefits of Drip Irrigation
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 weed growth.
* Saves time, money, and water because the system is so efficient.
* Decreases labor.
* Increases effectiveness on uneven ground.
* Reduces leaching of water and nutrients below the root zone.
Drip Irrigation System Design and Components
The main components of a drip irrigation system (see graphic below) 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 water source. The combined length of the mainline and sub-main should not exceed 400 feet.
The 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 doesn’t flow back into the pipes and contaminate your main water source.
Pressure regulators are needed if the 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.
Tubing 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, see Water Wisely.
Because 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 plants require per day and the emitters’ flow rate. 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 plant disease.
Check 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 used. However, regardless of the size of the area being irrigated there is an initial upfront cost for standard items such
as the valve, pressure regulator, and backflow preventer.
Drip emitter tubing provides 90% watering efficiency, right at the root zone. Protects the emitter from root intrusion, creating a long-lasting, low maintenance sub-surface drip irrigation system for use in organic gardens or shrub and groundcover areas. Avoiding water-waste
Reducing run-off and leaching
Reducing evaporation enabling reuse of wastewater