How ETwater Applies Proven Science to Water Management

ETwater uses the scientific principles of evapotranspiration, or ET, to determine a plant or turfgrass' true watering needs. ET is a measure of the amount of water loss occuring from soil evaporation and plant transpiration. Understanding rates of evapotranspiration on a day–to–day basis is critical to delivering more precise irrigation schedules at the landscape site.

Using ET values and rainfall data gathered from local weather stations, the ET Water patent-pending system of software algorithms calculates the appropriate base watering schedule for each landscape station (or zone). Then, as weather changes, or, as the crop coefficient or other landscape variables are changed, the schedule is automatically adjusted. The ETwater smart controller, which contains a telecommunications link to the ET Water central computers, is the essential link between the online irrigation scheduling engine and the landscape.

The Water Balance Method
The ETwater method for developing a precision watering schedule uses the Water Balance Method, a long standing and proven approach to managing irrigation and achieving optimum plant health. Using the Water Balance Method, the amount of water applied during each irrigation event actually remains constant. This amount is based on a pre-defined soil moisture depletion level, typically around 50% of the moisture in the plant root zone.

ET and rainfall data gathered from local weather stations are used only to vary the frequency of irrigation. ETwater software automatically delays watering until a pre–set soil moisture depletion level is reached, based on the measured daily ET rate.

Landscape Factors
The ET Water central computer automatically generates the daily watering schedules for each station on the landscape. Customized run and soak times for each station are based on such variables as:

The particular zone's sprinkler application rate Sprinkler systems, for example, apply water at a much faster rate than drip systems. The ET Water software automatically allows for such differences, adjusting watering intervals and run times. The amount of water applied for any sprinkler station will also take into account the distribution uniformity of the sprinkler system.
The soil intake rate Sandy soil takes in water much faster than clay and has a much lower holding capacity. Recognizing the differences in soil intake rates and holding capacities is a vital part of the ET Water software algorithms. These soil factors affect the frequency of irrigation as well as the length of cycle and soak times.

Slope condition If part of the landscape has a severe slope, water absorption will occur much slower than it does in flat areas, necessitating shorter runtime cycles and longer soak periods. Understanding slope factors in each zone of your site permits ETwater to control harmful runoff.

The mix of plant types served by a single station ETwater will always water to the most demanding plants on a station, assuring plant health at all times for the neediest plants in a mixed plant use setting.

All of these factors combine to make the ETwater system unique, efficient and effective. In fact, in a recent study conducted by the Center for Irrigation Technology at California State University, Fresno, ETwater scored 100% on Adequacy (the ability to meet the plants' water needs), and 98.5% on Efficiency (the ability to irrigate without over–watering or creating runoff).

Making Irrigation Science Simple For You
After more than three years in development, ETwater has used science and technology to deliver on the promise of easy–to–use irrigation control. Simple? The goal for ET Water is to make it simple for our customers.

Now you understand more about what makes our intelligent watering system work. The right amount of water is applied at the right time to satisfy the landscape's water requirements. And by using scientific principles to solve the long–standing problem of inefficient irrigation, ETwater fulfills its mission to landscape owners and managers. And, the benefits of using the ET Water science–based approach are clear:

Healthier plants and turf
Significant reductions in water waste — and the associated pollution from landscape chemicals
The potential for major water cost savings among both commercial and residential water users