The answer to that question is, of course, yes—plenty more. While drip irrigation remains a tremendously efficient way to deliver water right to the root zones of plants, there are many, many other devices, practices and strategies at our disposal when conserving water is the primary goal.
We can turn to low-flow irrigation heads, smart controllers, rain and soil moisture sensors, micro sprinklers and bubblers, precision sprinklers, rotating sprinklers, drought-tolerant plantings, rain gardens, graywater and rainwater recapture systems. And then there’s simply reducing waste.
It’s good that we have so many ways of conserving this precious natural resource. Experts predict that conserving potable water is going to become more and more critical in the drier decades to come. We need to find ways to use less of it on our landscapes.
This is not, in any way, to bash conventional spray and rotor irrigation.
When properly installed, maintained, and intelligently managed, these systems don’t waste water.
Using drip and micro irrigation
Depending upon whom you talk to, the terms ‘micro irrigation’ and ‘drip irrigation’ are often used interchangeably. This gets confusing.
“Historically, the three terms ‘micro,’ ‘drip’ and ‘low-volume’ irrigation have meant exactly the same thing,” said Robb Kowalewski, product manager for micro irrigation at Hunter Industries in San Marcos, California.
“But, we’re coming into a new world where that’s no longer the case. For those who’ve always known ‘low-volume irrigation’ to mean drip, the definition is slowly evolving to include other products that also put out a lower volume of water, such as precision sprays and rotating nozzles.”
Here’s the big difference: Conventional sprays and rotors deliver flows in gallons per minute (gpm). The low-volume, micro, and drip world works in gallons per hour (gph). Anything from 30 gph down to 0.4 or 0.5 gph is considered to be ‘low-volume.’ Rotating nozzles that can deliver as low as 0.4 gph definitely fit in this category.
Bill Hutcheon is president of Longwood, Florida-based Antelco, a company that makes drip and micro irrigation components. “Micro sprinklers and bubblers are used in pointsource irrigation, the same types of applications where drip is used, such as landscape beds or containers,” he said. “They’re all water conservation products.”
Henry Soto, service and irrigation manager at DeSantis Landscapes, Inc., Salem and Portland, Oregon, provides an example of how micro and drip irrigation components are used together.
“We tend to not set up whole zones with just micro sprinklers or micro sprays. Sometimes we’ll have annual plantings in a drip zone, something that needs a little bit more water, so we’ll add a couple of micro sprays to give them a little extra water. We’ll use the bubblers on containers, which everyone in Portland seems to have.”
It’s surprising to hear, but “Drip doesn’t automatically save water,” said Brian E. Vinchesi, principal and president of Irrigation Consulting, Inc., Pepperell, Massachusetts. (He’s also a CLIA, a CIC, and has a host of other certifications.) “I can mis-schedule a drip system as badly as I can mis-schedule a spray one. It’s all about running and managing a system correctly, not the type of equipment you use.”
“People think that drip waters very slowly, but it doesn’t,” said Vinchesi. “It has a relatively high precipitation rate. If I’m using dripline on 18-inch row spacing with a 12-inch emitter spacing, with 0.9 gph emitters, my precipitation rate is just a hair under one inch an hour, which is as much as a spray head.”
Kowalewski agrees, saying, anybody can put in a drip system and say, ‘I’m saving water now,’ but if they don’t have good practices, it simply won’t matter.
“I can easily show you scenarios where, if you’re using dripline with one-gph emitters, 12-inch spacing and 12-inch laterals, your precipitation rate is 1.6 inches per hour. A standard MP Rotator applies water at 0.4 inches per hour, which is one-quarter of that. If you run them both for 30 minutes, you’ll see that the drip system dispersed more water.”
End-users and homeowners often complain that they can’t see subsurface drip systems working, so they’ll increase the run time and defeat the entire purpose. That’s why some contractors and specifiers will use low-volume overhead sprays instead of drip, even though drip saves more water.
A clever solution one manufacturer came up with to address this problem is a pop-up indicator for its subsurface drip systems. When the system is running, the indicator is up; when it’s not, it’s down, kind of like the little button that pops out when the Thanksgiving turkey is done.
There are many situations where drip would seem to be the best solution, but can’t be used. Vinchesi says that in New England and most of the Northern states, a lot of customers won’t allow drip to be installed.
Most of his institutional clients, hospitals and universities, don’t want to deal with the maintenance thousands of feet of dripline would require, especially when you add the stress of freezing temperatures. They ask him to find other ways to be water-efficient.
Some of those ‘other ways’ include using smart controllers, usually ones that are soil-moisture based, or at least, climate-based. Vinchesi will specify rain shutoff devices in addition to soil moisture sensors, and that all the spray heads be pressure-regulating types.
Soto’s company uses advanced central control systems, paired with smart controllers, to manage irrigation for its large commercial customers. He says this provides an even higher level of water conservation, as he can input soil types, sun exposure, plant types, the maturity of the plants, sprinkler types, and even water depletion rates into the smart controller.
“We hook them up to moisture and rain sensors, weather stations, and flow monitoring devices. We let the weather information schedule the controllers.” Of all those things, he thinks that flow monitoring capability is the most valuable in saving water.
“We’ll run a zone, and register exactly how much water is moving through that pipe. If that flow is ever, say, ten percent higher than it should be, the monitor will tell the controller to shut the system down, and send us a message that we’ve probably got a break somewhere. It won’t irrigate again until we tell it to.”
Since rotary and high-efficiency nozzles can have flows as low as 20 gph, they fit under the heading of low-volume irrigation.
“When it comes to California’s Model Water Efficient Landscape Ordinance (MWELO) and other regulations, rotating nozzles have their own category,” said Kowalewski. “They’re being included where others are being excluded.”
Bob Dobson, president of Middletown Sprinkler Company, Inc. in Port Monmouth, New Jersey, recalls retrofitting some parking islands on a commercial site. “In one spot, the island was only 20 feet wide. They had 40-foot radius rotors on them, throwing water 20 feet out into the parking lot. Half of the water was going out onto the paved area.”
“We retrofitted all the islands with rotating-nozzles, which dramatically improved both the uniformity and the efficiency. They are no longer watering the parking lot.”
Vinchesi’s company also uses a lot of rotating nozzles. “There are a couple of things those will get you,” he says. “They have a lighter precipitation rate, which gives you more incremental time to program. If I want to put down the same amount of water, there’s a big difference between whether it takes me ten minutes or 20 minutes. If it’s longer, I get to play with it more.”
Signature Landscapes in Reno, Nevada, retrofits with rotary heads to reduce water demand on turf applications. However, CEO Lebo Newman says there’s one drawback to doing that, particularly on large commercial sites.
“We still have watering restrictions here in Reno, even though they’re saying we have plenty of water. Because rotating heads deliver water more slowly on large sites, you can end up exceeding your ‘watering window’ (the span of time you’re allowed to water for),” Newman explained.
There’s one ‘trick’ he’s successfully employed in such situations. “If the meter will allow more water through it, you can increase the mainline size to get more water through quicker. Then you can run more valves at the same time.”
In some situations, Soto has had to do something that you’re never supposed to do—combine nozzles with different precipitation rates and modes of delivery.
“They’ll tell you never mix a spray head with rotating nozzles,” said Soto. “But every situation is unique. I’ve had plenty of sites where half of a zone is shaded, and the other half, sunny. The shady area is always too wet, because it doesn’t use the water as fast as the sunny area. In cases like that, I’ve put rotating heads on the shady side and left spray heads on the sunny part.”
Installing check valves
Russ Jundt, founder and COO of Conserva Irrigation of Ham Lake, Minnesota, never met a check valve he didn’t like. “We put them in every single one of our heads,” he said. “They hold the water inside the pipe and prevent lowest-head drainage. They cost about a nickel apiece, and can save thousands of gallons every year.”
He explained that, once a system finishes a cycle, gravity causes the remaining water to leach out of the lowest head on the zone. As much as 18 to 50 gallons of water can be lost this way, every time a system cycles off.
“The biggest thing for water conservation is to follow the basics,” said Vinchesi. “There are still a lot of people out there who don’t match the precipitation rates of their sprinklers. That’s like, Rule Number One, and has been for 30 years. But a lot of guys still don’t do it. If you don’t, you’re going to waste a lot of water.”
Matched precipitation rate rotary nozzles are helping Dobson conserve water in a current commercial retrofit. “In the old system, the full-circle and part-circle rotors were zoned together. An audit showed the part-circles applying water at twice the rate of the full-circles,” said Dobson.
“We’ve corrected some spacing issues and changed all the rotors out to rotors with the matched precipitation rate nozzles. Now, we’re getting a much higher distribution uniformity.”
“We can already see the difference in the turf. Areas that used to be saturated by the part-circles no longer have that problem. We were able to reduce the run times on all the zones.”
Dobson knows what a valuable tool a formal water audit is. So does Jundt. Some of the larger commercial property owners he works with will focus only on one aspect of conservation, thinking that’s the answer. But a water audit shows his clients the full picture.
“We worked with one of Minnesota’s largest HOAs recently. The owners wanted to go ahead and put in smart controllers, because they’d just learned about that. We said, ‘That’s great, but first, let’s do an audit.’ There were 23 water sources, 464 zones and 7,800 heads. The audit revealed 2,208 broken sprinkler heads.”
“We were able to show them that simply putting in smart controllers would have been a Band-Aid, not a solution.”
Clearly, a lot of water can be saved by simply fixing what’s wrong with an existing system. Any system that’s been in place for a substantial period of time probably has issues. “When I moved into my new home, one of the first things I did was repair the old irrigation system,” said Kowalewski. “It had conventional spray heads, didn’t have head-to-head spacing, and the distribution was all over the place.”
He dug up the entire system and respaced the heads. That alone raised the system’s efficiency from about 35 or 40 percent to around 55 percent. Later, he exchanged the spray heads for MP Rotators, bumping it up another 10 or 15 percentage points.
Drip irrigation remains a great tool for conserving water. But it isn’t the only tool. Thanks to the ingenuity of irrigation and landscape contractors, and the innovation of irrigation equipment manufacturers, we have many, many more at our disposal.