Discussion: Inside Evapotranspiration

January 2005


Golf courses and agricultural irrigators have relied on expensive weather stations to provide localized weather data for years to boost efficiency and save millions of dollars on water bills. Now new products are beaming weather data directly to smaller users, allowing them to save money and potentially saving millions of gallons for drought-stressed municipal water providers. North Logan, Utah-based Irrisoft, Inc. and Petaluma, Calif.-based Hydropoint Data Systems Inc. are two companies seeking to make weather specific irrigation controllers standard everywhere.

Steven Moore, Irrisoft, Inc.

The introduction of affordable evapotranspiration-based sprinkler system control is altering the irrigation world, says Steven Moore, president of North Logan, Utah-based Irrisoft. Five-plus years of drought make the technology even more important.

The scarcity of water, especially in the west, is giving rise to extensive xeriscaping. Many locales are introducing ordinances that strictly limit the percentage of a property that can have landscaping. “Many studies have shown that many sprinkler systems use twice as much water as the landscapes needs,” Moore said.

“To conserve our water resources we need to start by improving the way water is managed. An ET-based sprinkler system can usually save 20 percent to 30 percent and often much more.

“I think that people should have the choice (between cutting area and cutting water consumption),” Moore said. “But at the same time, people should be held accountable. It’s not in the community’s interest to let people abuse or overuse the supply of water. Using technology to improve water management is much cheaper than relandscaping.” Irrisoft’s system transmits the data by radio to individual controllers, which increase or limit water based on its day specific need. ET is calculated using basic weather information including humidity, temperature, wind and solar energy.

The technology has tremendous growth potential, as Moore estimates that less than five percent of irrigation systems use ET input.

“There are cases where people are using 300 inches of water a year when the need only 25,” he said. “That’s the extreme. It’s not common, but that degree of misuse shouldn’t be allowed.”

“So if we can cut water use by a third we’ve achieved our conservation goals without having to reduce the size of the landscape.”

Irrisoft markets an ET-data-based system called Weather Reach.

Irrisoft Systems Q & A

What is Weather Reach?

Weather-based technology used to optimize irrigation water use.

How does the system save you money?

Most landscapes are over-watered because sprinkler timers can’t compensate for daily weather changes. Weather Reach uses weather data to automatically manage watering schedules, resulting in a 20 to 50 percent water savings.

How does Weather Reach work?

Weather data from local weather stations is sent via wireless broadcasts to Weather Reach Receivers. Using information about your landscape and local weather data, the Weather Reach Receiver adjusts your irrigation to deliver the optimum amount of water.

What happens when it rains?

Rainfall measurements at your property or from the weather station will be used to postpone irrigation according to the amount of rain that fell.

How much time does the system take to operate?

Once your Weather Reach Receiver is installed and adjusted, your system is totally automated-no need to adjust your timers when the season changes.

How much new hardware will I need?

As the owner of a Weather Reach Receiver you receive data from a locally installed, high quality, weather station that is maintained by your local service provider. A weather receiver is easy to install and works with your existing irrigation controller.