Smart controllers make watering adjustments by measuring the amount of moisture absorbed into the atmosphere through evaporation from the soil and transpiration from plant surfaces, a process called Evapotranspiration.
Climate conditions like temperature, relative humidity, wind speed, and solar radiation affect local ET values. With programming for each zone's plant type, soil, slope, and shade or sun exposure, smart controllers promote a healthier landscape that uses less water.
How Smart Controllers Obtain Weather Data
On-site Weather Monitors
Sensor-based controllers use an onsite weather monitor to calculate real-time factors and adjust irrigation timing. The factors include: temperature, rainfall, humidity, solar radiation, and soil moisture. These controllers often rely on historic weather information programmed for that site’s location in the memory and modify daily irrigation requirements based on its sensor’s readings.
Signal Based Off-site Weather Data
A signal-based controller receives regular updates via radio, telephone, cable, cellular, web, or pager signal from a local weather station or a network of weather stations. Normally a monthly or yearly subscription fee covers the cost of servicing the evapotranspiration data transmitted to the controller.
On-site Soil Moisture Sensor 
Moisture-based controllers use a moisture sensor to measure the water content of the soil. This measurement determines the amount of water necessary to replenish the soil. The sensor typically is wired electronically from the sensor to the controller.
Smart Controller Product Testing
The Irrigation Association’s Smart Water Application Technology (SWAT) program, which partners with water purveyors and the irrigation industry to promote water use efficiency, provide product testing results.
According to SWAT, “‘Smart controllers for smaller applications have become available more recently, and field testing has proven they can successfully reduce outdoor water use—by as much as 20%-40% annually—while maintaining, and often enhancing, the health and beauty of the landscape.”
View Smart Water Application Technology (SWAT) smart controller testing results, More.
Find out more about:
Qualifying smart irrigation controllers and manufacturers, More.
Questions?
If you have any questions or concerns about finding the right smart controller technology for you, please contact the city’s water education coordinator at 972-292-5814 or by email.