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Outdoor water use in the United States averages over 9 billion gallons per day. That water is used primarily for landscape irrigation and it is estimated that as much as 50% of it is wasted due to overwatering. Smart irrigation systems save water by only applying water to the landscape when it is actually needed.
Fixed-schedule irrigation timers help to keep residential and commercial landscaping healthy and green. By eliminating the need to remember to water lawns, shrubs and trees, this basic level of automation ensures that the landscape gets moisture regularly. Fixed-schedule systems actually contribute to the water waste, though. Their set-and-forget operation often results in too much water being applied when it is not needed. They simply don’t take current conditions into consideration. Smart irrigation systems are the solution to the problem and studies indicate water savings of 40% to 70% through the use of the technology.
Smart irrigation systems save water by making scheduled irrigation more efficient through the use of technology that allows the system to adjust to current conditions. The systems utilize localized weather data, moisture sensors or a combination of both to provide only the amount of water needed.
Types of Smart Irrigation Systems
There are essentially two ways that smart irrigation systems determine whether irrigation is needed. One relies on publicly available current weather data and the other uses soil moisture measurements. In either case, these controllers can be deployed as complete systems or as upgrades to compatible timer-based systems.
Weather-Based Controllers
As the name implies, weather-based controllers evaluate current weather conditions to calculate water need. These systems are often referred to as evapotranspiration (ET) controllers because they primarily rely on calculations of the amount of water that is evaporating from the soil surface. Using weather data such as temperature, relative humidity, solar radiation levels and wind speed, ET controllers determine the amount of moisture the landscape is likely to lose over a period of time. The data is combined with site-specific variables such as soil type, plant moisture requirements and irrigation rate to precisely calculate when supplemental water is needed.
There are three types of weather-based controllers:
- Signal-based controllers use a wireless connection to publicly available current meteorological data. Using this, they calculate ET values and then adjust the irrigation schedule accordingly. Such systems are dependent on the availability of localized data. Some areas may have data available that is accurate within a square mile. Meanwhile, others may not have localized data at all.
- On-site weather measurement controllers are much the same as signal-based controllers. However, they use weather station data gathered on-site to calculate ET measurements. This type of controller requires the deployment and upkeep of weather stations. That said, it can be used in areas where public data connections are not available.
- Historic ET controllers use regional water use data collected over past years to calculate the probable need at any particular time. The resulting water use curve can be adjusted for temperature and solar radiation.
Sensor-Based Controllers
Another way of determining the need for water is by physically testing the amount of moisture in the soil. Sensor-based controllers do just that and use the data to adjust the watering schedule as needed. Sensors are located in the soil beneath turf, trees and shrubs where they measure the amount of moisture available. That data is transmitted to the controller which adjusts the irrigation schedule in one of two ways:
- Suspended cycle controllers provide water according to a timed schedule, but the controller is programmed to skip the next irrigation cycle if adequate moisture is detected.
- Water-on-demand controllers do not follow a pre-programmed schedule, but instead activate an irrigation cycle if sensors indicate a low moisture condition. When properly calibrated with the right amount of sensors, water-on-demand systems are extremely efficient.
Smart Irrigation System Programming
It’s important to note that the optimal efficiency of smart irrigation systems is highly dependent on accurate programming. Often, default settings are configured to meet 100% of an average landscape’s theoretical water needs. A mixture of plant species, different soil types and local microclimates will all affect the actual water needs. Healthy mature plants will typically require less water than recent plantings. Fine tuning the site-specific parameters is important to achieve the best results.
Monitoring and Maintaining Smart Irrigation Systems
Smart irrigation systems automate the watering process, but periodic monitoring and maintenance are still necessary. Particularly with a newly installed system, homeowners or property managers should take time in the first few weeks to inspect the condition of their landscape. Changes of season are another time that systems should be checked for proper irrigation levels.
Lush green foliage is ideal, but may indicate that a little less water could be used. Excessively moist soil also indicates that programming could be dialed back. Wilting or browning foliage, of course, means that more water is needed. Variations between zones and differing water needs must be observed and accounted for. Rainfall sensors that are incorporated into most systems should be periodically checked to make sure they are free of debris that will inhibit proper operation.
Finding the Right Solution
In the decades since smart irrigation systems were introduced, quite a variety of options have come to market. The U.S. Department of Energy provides a lot of helpful information. They offer notes on what to keep in mind when designing a smart irrigation system. The EPA also provides good assistance with their WaterSense certification. WaterSense-labeled controllers are certified to meet plants’ water needs without overwatering. Of course, the experts at Jerry Pate Design are also here to help. Allow us to assist you in choosing the right smart irrigation system for your landscape.
