Weather-based controllers monitor changing weather conditions to prevent unnecessary watering. These products are also referred to as climate-based controllers, climatologically-based controllers and smart controllers.
Weather-based controllers use sensors to calculate evapotranspiration, the amount of water that evaporates from the soil surface or is used by the plant. Based on local weather conditions, these smart controllers automatically adjust the irrigation schedule to deliver only enough water to meet the plant’s or soil’s needs.
Different controllers use different sources of weather data. Controllers use on-site weather sensors, data from a local weather station or data from the internet. Weather-based controllers can be retrofitted on new or existing irrigation systems.
SWAT Testing Protocol
SWAT began developing a testing protocol for weather-based controllers in April 2003. Version 8 of the protocol was approved and adopted in September 2008.
WaterSense Testing Protocol
The U.S. Environmental Protection Agency’s WaterSense program began labeling weather-based controllers in 2012. WaterSense criteria are based on the SWAT testing protocol but include modified requirements for minimum runtimes, missing weather station data, rainfall requirements and calculating the water balance.
Product Testing Results Based on SWAT Protocol
10/30/2014 Rachio IRO 16 Zone
10/30/2014 BIT ICS-One
08/02/2013 Weathermatic Smartline SLW1
08/02/2013 Weathermatic Smartline SLW-15 or SLW-5
Products should be retested or reviewed every three years to ensure performance reports are relevant to current products being sold. Products with test results older than three years have been removed from the list above. Details about using WaterSense test results to create SWAT performance reports can be found here.
For questions about SWAT or weather-based controllers, contact the Irrigation Association (703.536.7080; email@example.com).