DeeAnne McClenahan is convinced that water-sensor irrigation is worth the initial investment. But the senior director of procurement and sustainability at Greystar Real Estate Partners has a tough time trying to persuade property owners to invest thousands of dollars on the watering equipment.

When it comes down to it, McClenahan can usually make the case with numbers.

One of the most compelling examples she likes to use is an 830-unit property in Phoenix that saved more than $23,000 in just one watering season. The key to the case is a computerized irrigation system that measures all of the factors that go into keeping plants and grass healthy.

The Charleston, S.C.-based manager and owner began investing in smart watering by purchasing the HydroPoint WeatherTRAK system in May 2012 and has since installed it in at eight properties. Temperature, rain and moisture levels are measured by the system and the amount of water needed on a given day is adjusted accordingly. Traditional irrigation systems on timers can’t gauge weather or adjust to temperature changes.

“The timers don’t know when it’s hot or when it’s windy or when it rains,” McClenahan says. “[This] system does. If it can tweak it for a minute here and there, especially in those hot months, then we know we’re either under or over-watering.”

Martin Sprang, vice president of asset quality and service at Denver-based AIMCO, has also seen firsthand the savings resulting from smart watering systems. The company used about 20 percent less water for irrigation on average across 37 properties using the smart systems, Sprang says.

“It’s almost become a necessity,” he says. “It saves us tens of thousands of dollars.”

However, AIMCO doesn’t use the system at every property because the hefty cost of installation sometimes outweighs the return.

“We use them mostly in the Southwest: Texas, Colorado, Arizona, California,” he says. “And we have one system in Georgia. The return on investment doesn’t make sense at all properties but we water year-round in the Southwest.”

McClenahan says that, when presenting the proposal to owners, the initial cost of installation is a hefty sticker shock. But the savings give a relatively fast return on investment, she says.

“I have a list in front of me of almost 20 properties that have a payback of under three years and most of them are under two years,” she says. “Then, with the ones that we installed, some of them were projected to be one. Then there was one that was projected to be two and a half, and the payback was just barely after the first summer.”

One of the largest problems with the systems are humans tampering with the computer, both executives noted.

“We put language in [our landscaper’s contracts] that they’re not to change the settings on the controllers,” Sprang says. “Whenever we have a problem, it always goes back to the [controller’s settings] being changed.”

Lindsay Machak is an Associate Editor for Multifamily Executive. Connect with her on Twitter @LMachak.