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Drip Irrigation:A Water Conserving Solution

JANET REILLY | Drip Irrigation - Low Flow

Drought conditions... Water restrictions... On-going scrutiny over irrigation practices... All have made landscape irrigation professionals’ jobs more challenging and demanding as they strive to manage and conserve water more wisely.

In the face of adversity, the search continues for solutions to prevent excessive water use while allowing landscape irrigation professionals to effectively do their jobs. Irrigation manufacturers are an integral part of the solution and have made strides in recent years with the design and development of more application-specific and efficient products. And contractors are making a more concerted effort to install these products, which help conserve water, better serve their customers and improve their bottom line.

While the market offers a number of newer products engineered for precise water distribution when and where water is needed, no one irrigation management approach or practice may have a greater impact than landscape drip irrigation. When used to water plant areas, drip irrigation is a viable solution over traditional irrigation systems that feature spray heads or rotors. In fact, drip systems can result in water savings of 30 to 65 percent compared to traditional systems.

In a time when, more than ever, every drop of water counts, drip irrigation can be invaluable to the environment and to a contractor’s business.

What is drip irrigation?

Landscape drip irrigation is a method of delivering water slowly, at low pressure, at or near the root zone of the landscape plant material. It is often referred to as targeted or precise watering, because drip irrigation allows you to target the precise area that you want to irrigate. Drip irrigation systems typically operate between 15-50 psi, and flow rates are measured in gallons/hour (GPH) versus gallons/minute (GPM).

Where should drip irrigation be used?

A proven irrigation tool initially designed for the agriculture industry, drip irrigation can be effectively applied to any non-turf area, large or small, including shrub beds, flower gardens and hard-to-water areas. Areas sensitive to overspray, high traffic areas, windy areas and areas with mixed plantings are also great applications for landscape drip systems. Most notable is its efficiency in areas made up of a sparse configuration of plants and/or flowers. A drip irrigation system can be positioned to distribute water slowly at or near the plants’ roots, while avoiding to water the soil between plants.

Drip irrigation can be beneficial for use in both residential and commercial settings. Some specific sites in these markets that might feature low-volume irrigation include condominiums, corporate campuses, courtyards, medians, and planting areas near sidewalks.

Benefits

As a result of drought conditions and water restrictions throughout much of the country, the concept of drip irrigation has caught on with more and more contractors in recent years. In addition, its popularity has increased due to contractors’ desires to simply find a more efficient and cost-effective way to meet their customers’ demands and a way to differentiate their business.

In some areas, drip is the only form of irrigation allowed. Industry professionals also realize that landscape drip helps alleviate negative public perception of irrigation and the concern over our nation’s decreasing water supply.

Drip irrigation’s popularity may continue to grow as its benefits become more evident. Increased education and awareness, the availability of more technologically-advanced products and word of mouth exposure are all keys to heightening landscape drip irrigation’s role as a significant water-conserving irrigation method.

Water conservation

The most recognized benefit of drip irrigation is that it saves water. With the drip of an emitter, precise amounts of water are delivered directly to the plant’s root zone. Drip irrigation gives contractors much more control over where the water is distributed and where it is not distributed, allowing you to use only the exact amount of water needed for each plant.

Landscape drip irrigation also saves water because it is subject to much less evaporation as the water is distributed. Windy conditions do not alter the drip process as it does spray patterns. And there is no concern of over-spraying your intended planting area and soaking sidewalks, cars, buildings, roads or parking lots. This is a waste of water, it reflects poorly on the landscape irrigation industry, and it could become a liability.

Because water is delivered slowly and directly to the root zone, water or soil runoff is significantly reduced. This is especially critical when irrigating on uneven ground or slopes, where the potential for runoff is greater.

In addition, water is applied precisely where it is needed within the planting area. Your biggest savings come when you can avoid unnecessarily watering soil between your plants in sparse gardens or flower beds. Drip irrigation is generally considered to be 90-95 percent efficient versus 30-60 percent for sprays and rotors—and your savings increase even more when you eliminate watering the soil in-between your plants.

Improved plant health

Drip irrigation is a targeted watering technique that allows each plant zone to receive the exact amount of water it needs to thrive. With traditional irrigation, every plant in a zone receives the same amount of overhead spray. With drip irrigation, each plant can receive its ideal amount of water by using the correct size and amount of emitters, bubblers or micro-sprays.

Soil aeration is improved as drip irrigation slowly permeates the soil and creates less compaction. This helps improve root growth and results in a healthier plant. And different drip products can distribute the water to the foliage itself or only to the soil, depending on what is best for a specific plant. Overhead water can create unsightly brown spots on some flowers, while it can aid the health of other plants. Drip irrigation allows you to tailor your watering to meet the requirements of all plant types.

Cost-effective

Installing and maintaining a drip irrigation system saves both time and money. With a proper installation design in place, less labor is usually required to install drip systems and the overall material cost is oftentimes less expensive as well. As a result, contractors will see increased productivity and profitability at the end of the day.

Offering drip irrigation installation to your customers in addition to your other services will help expand your business opportunities and position your company as using water intelligently.

Design Flexibility

Installation of drip irrigation systems offers more flexibility, literally and figuratively.
Flexible, polyethylene tubing allows you to conform to the plant area you are working in. PVC pipe, used with traditional systems, can be used as tubing with drip systems as well, but flexible tubing is advantageous because it can be placed in any direction and does not have to follow a straight line. This gives contractors more flexibility in their design and allows them to install the tubing exactly where it is needed and will help the irrigation system achieve maximum efficiency.

Contractors need few special tools in order to install and maintain drip systems. The basics of hydraulics and flow are similar for drip systems compared to traditional systems.

And replacing parts because of vandalism should not be a concern. Emitters, a small device that controls the flow of water going to the soil, and drip line can be installed so that they remain relatively hidden from view in flower beds or gardens near high-traffic areas. There are several products available that are designed to help make drip irrigation systems vandal-proof, whether you are using flexible tubing or PVC pipe. Some emitters can pop up and down, retracting flush with the grade when not in use and keeping them out of sight. Other products are designed to make it easy for contractors to install tubing below grade.

Design installation: Things to know

A perception exists that installation and maintenance of a drip system is more labor-intensive and complex. As mentioned earlier, this is not true. However, more thought is required up front when designing a drip system compared to a traditional system to achieve maximum water distribution efficiency. You want to ensure that the proper amount of water is distributed precisely at the root zone of the plants.

A few key variables to think about include pressure regulation and filtration, product selection and proper design.

Pressure regulation/filtration

Drip irrigation requires low volume and low pressure to operate effectively, distinguishing it from traditional systems. As a result, every drip irrigation system should include filtration and pressure regulation.

Pressure regulation ensures that the pressure entering the system does not exceed the maximum operating pressure of drip irrigation. The optimum operating pressure of a drip system is between 15 and 50 psi.

Filtration, meanwhile, ensures that large particles do not clog the downstream components, and that smaller particles won’t impede the water flow from the emission device. Installing the proper filter for a given application will help minimize the amount of maintenance needed. Cleaning the filter is often required periodically, but self-cleaning filters exist that are ideal for certain applications, and these virtually eliminate maintenance. Complete control zone kits are available on the market, which include all of the components (valve, filter, pressure regulator) necessary for a drip irrigation control zone.

Product selection

A proper design also means using the proper products. Contractors can choose the right type of dripline or drip emitters taking into account the plant’s water requirements, the climate, the soil and whether the irrigation zone area features dense or sparse plantings.

One of the biggest mistakes contractors make in the design is using the same product for all applications. Because different plants require different amounts of water, it’s important to use different emission products, if necessary, to distribute the proper amount of water to each plant in the same drip zone. This simply cannot be achieved using a traditional system.

For dense plantings, inline emitter tubing is usually used due to its ease of use. However, polyethylene tubing with pop-up micro-sprays or PVC pipe with poly-flex risers and bubblers can also be used. For sparse plantings, polyethylene tubing with emitters or PVC pipe with poly-flex risers and emitters are recommended, so you can target each plant and not water the soil in-between the plants.

Which emission device to use is often the most confusing choice in drip irrigation. Emitters come in many different flow rates and styles. Some emission devices are designed specifically for dense plantings and are considered broadcast emission devices. These include in-line emitter tubing, micro-sprays, misters and pop-up low-volume sprays. Annual flower beds are one example of where pop-up sprays with low-flow nozzles would be beneficial.

Other emission devices are better suited to sparse plantings, but can also be used to supplement broadcast emission devices in dense plantings when a certain plant needs more targeted watering. These include single-outlet emitters, multi-outlet emitters and bubblers. These emitters come in a range of flow rates (from 0.5 to 24 GPH) and inlet styles (barbed, threaded, spiked). The plant type, the soil and the type of installation will determine which emitter to choose. To satisfy the different water intake requirements of plants in one irrigation zone, emitters can distribute different volumes of water using the same run time.

Proper Design

A proper design should take into account the evapostranspiration (ET) rates for the given area, soil type, plant/species type, size of area and micro-climate. These factors need to be considered so that each plant receives the correct amount of water to keep it healthy and that water is not wasted.

Hydraulic calculations are necessary in drip irrigation designs, just as they are with traditional systems. You must ensure that you size your header correctly for the amount of flow required, and that pressure loss is taken into account when you calculate the lateral lengths of your tubing runs. Pressure should not exceed 50 psi or go below 15 psi at any point in the system after the pressure regulator.

A landscape drip design guide is a helpful tool that shows maximum lateral lengths and header sizes based on flow rates, helping determine calculations. You may find an online example by visiting www.rainbird.com/pdf/turf/DripDesignGuide.pdf.

One advantage to drip systems is that they can be easily changed to meet customers’ needs if, for example, the customer changes flower beds on a regular basis. A change in flowers may require a change in irrigation design. In many cases the drip zone can be dug up without disconnecting the irrigation system and repositioned to efficiently water the new flower beds.

And contractors have choices in water supply connections when installing a drip system. The system can draw from an outside faucet, or can be installed to an existing, traditional system, allowing you to schedule watering times with a battery controller or existing sprinkler timer.

Drip irrigation’s future bright

The landscape maintenance industry continues to rise to the challenge of addressing concerns over water conservation. Drip irrigation will continue to serve as a win-win for the industry as it becomes more widely understood and as more advancements are made in equipment, benefiting the environment and the contractors who use it.

Janet Reilly is the Landscape Drip Marketing Manager at Rain Bird Corporation. For more information about drip irrigation, contact her at (626) 812-3673 or jreilly@rainbird.com, or visit Rain Bird’s Web site at www.rainbird.com.

AUGUST 2004

 
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