Water-Saving Sensors Go Toe-to-Toe? The Winner Will Surprise You

By Bernard Cardenas

Ever suspect that some of your neighbors apply too much water to their lawns? In some cases you might be right. To remediate this issue, the irrigation industry has developed products to reduce the amount of water wasted during landscape irrigation. 

Water waste adds up (via EPA WaterSense)

Among these technologies are rain sensors and soil moisture sensors (SMS). Rain sensors detect when sufficient rain has fallen and then bypass the irrigation timer’s schedule. Likewise, SMS can detect if the soil is moist enough (so that the lawn can withstand some extra days without watering) and then prevent scheduled irrigation events. 

Sensor vs. Sensor

In a recently published study researchers at UF evaluated the water savings potential of rain sensors and SMS in homes for more than two years. They compared their results to homes only equipped with irrigation timers. They also compared those results to homes that were provided both a rain sensor and educational materials. 

To evaluate if the homes in the study were applying the right amount of water, the researchers also estimated the water applied by the different technologies compared to a theoretical requirement (calculated using a daily soil water balance).

Palm Harbor, FL - where we lay our scene

The Location

In the vicinity of Palm Harbor, FL, a total of 64 homes supplied with reclaimed water for irrigation were selected for this study. Dedicated irrigation flowmeters were installed in every home to measure the amount of water applied. The 64 homes were divided in 4 treatments with 16 homes each. Treatments were: MO (monitored only), SMS, rain sensor, and rain sensor plus educational materials. 

The Results

By the end of the study, SMS-equipped homes were the only group significantly different to the MO homes. This means that the homes equipped with a rain sensor, or a rain sensor plus educational materials, did not save a significant amount of water compared to the MO homes.

Further, the homes equipped with a SMS reduced the average number of irrigation events per week, compared to the MO homes (1.7 vs. 2.7 events/week, respectively), decreased the depth of the weekly irrigation (22 vs. 42 mm, respectively), and applied 44% less water, over the 32 months of data collection. These savings were achieved with no adverse effects to turf quality.

These results indicate that the tested SMS can save a significant amount of reclaimed water, compared to the other methods/technologies investigated.

This paper is part of a series. Read part one here. And if you are attending the ASABE International Meeting in Orlando this month, the studies will be presented in session 138 on 7/18, 2:30pm - 5pm. Follow all our Orlando coverage on Twitter.