As the U.S. continues to struggle with drought, increased attention and need have been placed on efficient sprinkler heads for landscaping. Irrigation landscape professionals know of the importance of installing these water-saving systems, but it can be easy to forget the actual logistics of how they make a difference.
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From what it means to be efficient to how they reduce loss of water application, runoff and drift, irrigation landscape professionals unpack efficient sprinkler heads and how they play a vital role in today’s water usage.
Putting the ‘efficient’ in efficient sprinkler heads
It’s easy to read on a sprinkler head’s packaging that it’s efficient, but what does that really mean?
Jeffrey Johnson, senior product manager, commercial rotors and valves, Rain Bird, Azusa, California, says that for a sprinkler head to qualify as efficient, it depends on the distribution of water in a zone and is always less than 100% due to the application method, evaporation or runoff. The terms “distribution uniformity,” “coefficient of uniformity” and “scheduling coefficient” are common irrigation terms used to define the efficiency of sprinklers or emitters.
“Efficient sprinklers are those that discharge water with high uniformity and reduce the energy needed in the process of minimizing pressure or flow,” Johnson says.
Rick Hall, CIC, CID, CLIA, market development director for K-Rain Manufacturing Corporation, Riviera Beach, Florida, says that the simplest way to describe the right product choice is “the installation and use of a sprinkler head best suited for the area it will be watering.”
Efficiency is achieved in sprinkler design when it is able to regulate the water pressure down to the optimum level for the nozzle design and decrease water waste, says Brodie Bruner, executive vice president of Weathermatic, Garland, Texas.
“An efficient sprinkler incorporates a check valve and sufficient retraction spring strength to retain water in the system rather than allow low head drainage,” Bruner says.
Reduction of water application loss
One of the key components of efficient sprinkler heads is their ability to reduce loss of water application.
Alexis Deasy, senior marketing communications manager at The Toro Company, Bloomington, Minnesota, explains that there are multiple ways that efficient sprinkler heads successfully do this, such as by “reducing flushing at start-up so that there is little to no water waste or a head to pop-up, reducing misting and fogging at the head through pressure regulation and ensuring that when the nozzle is damaged or removed, wasteful geysers can be prevented.”
Pressure regulation and efficient nozzles like multistream, rotary or curtain nozzles also contribute to preventing water loss.
“Efficient nozzles provide uniform water distribution across the full range of water throw,” Johnson says. “Pressure regulation optimizes the water pressure to reduce wasted water due to misting. As a reference, every 10 psi regulated equals a 7% water savings.”
Hall adds that efficient sprinkler heads spray larger water droplets, thus reducing the effects of wind drift, “which can cause uneven watering or even carry water spray outside the intended area of coverage.”
Aaron Gagnon, associate product manager for large turf rotors, ST systems and accessories, Hunter Industries, San Marcos, California, also attributes efficient sprinkler heads’ capabilities to regulate pressure as a way to reduce loss of water application.
“Many spray bodies have pressure regulators in them,” Gagnon says. “Using this type of product will greatly contribute to using less water.”
Reduction of water loss via runoff or drift
Another significant component of efficient sprinkler heads is their ability to reduce water loss caused by runoff or drift.
Bruner notes that efficient sprinkler heads’ prowess in regulating pressure is key to avoiding drift.
“Many areas have water pressure over 50 pounds while a typical spray sprinkler is designed for optimum performance in the mid-30-pound range,” Bruner says. “Excessive pressure results in misting and drift as the water doesn’t effectively make its way to the root zone of the landscape.”
Bruner also highlights the clash between a spray sprinkler’s typical precipitation rate and soils’ intake rate.
“The typical precipitation rate of a spray sprinkler at 1.5 inches per hour is much greater than the intake rate of soils like clay at only 0.2 inches per hour,” Bruner says. “So, runoff is best reduced through run-and-soak cycling with a smart controller.”
Ensuring that water is applied at the correct rate for the soil type is another way that efficient sprinkler heads reduce runoff or drift.
“Tighter soils will need a slower application rate and larger water droplets to effectively absorb the water that is being applied,” Deasy says.
Reducing runoff or drift in system designs
Efficient sprinkler heads do most of the heavy lifting when it comes to lowering water use. However, contractors can help home or property owners decrease runoff or drift through calculated measures during the irrigation system design process.
Bruner stresses that it’s critical contractors consider a site’s water pressure in their design and equipment selection.
“Contractors should choose matched precipitation rate nozzles with proper head spacing to enable efficient and uniform watering,” Bruner says.
Hall advises contractors or property owners not run sprinklers during windy weather and shut the irrigation system off when runoff or pooling of water on the ground is noticed.
“Multiple start times better known as ‘cycle and soak’ allow the soil/ground time to absorb the spray,” Hall says. “A good general rule is to wait an hour between start times.”
He also urges contractors to use multistream or rotary nozzles as they help with soil absorption instead of wasteful runoff or drift. Contractors should also use up-wind/down-wind head spacing and low-angle nozzles to account for windy conditions.
Johnson suggests contractors use rotors and spray bodies with optional or standard integrated check valves to reduce runoff or low head drainage. Rotors or spray bodies with pressure regulation can also be used to optimize the output pressure of the emitter and eliminate misting and water waste. Contractors should set the edges of the rotor or spray nozzles to minimize watering hardscapes along the edges of turf and reduce runoff or drift. During windy weather, low-angle nozzles can be used to reduce drift.
“Periodic maintenance is also necessary to verify that the arc settings on the rotors and sprays have not changed over time,” Johnson says. “Cleaning the heads is also important to remove debris that may cause leaks or affect water distribution.”
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