Install rain and freeze sensors to existing irrigation system

Landscape water conservation practices can reduce water use, save money

Daily Light report
A  properly installed and functional rain sensor prevents unnecessary watering, which conserves our drinking water resources.

Since landscape irrigation increases water use by 35 to 75% during the summer irrigation season, Texas A&M AgriLife recommends landscape water conservation practices be adapted to reduce water use, save money and still maintain a beautiful landscape.  Water conservation is the easiest and least expensive method to make water resources sustainable for future use.

A rain and freeze sensor prevents an automatic irrigation system from applying water during rain or a freeze avoiding wasteful loss of water, over watering landscapes and preventing hazardous ice on the road, sidewalk or driveway.

A rain sensor keeps the irrigation system from starting or continuing after rainfall quantities of 1/8”, ¼”, ½”, ¾”, or 1”.  This is called the reset rate.  The reset rate refers to the amount of time it takes the rain sensor to dry out sufficiently for the sprinkler system to be allowed to come back on.  The time that it takes the rain sensor to reset for normal sprinkler operation after the rain has stopped is determined by weather conditions (wind, sunlight, humidity, etc.). Theses conditions will determine how fast the hygroscopic discs dry out, and since the landscape is also experiencing the same conditions, their respective drying rates will parallel each other.

There is an adjustment capability on the rain sensor that will slow down the reset rate.  This adjustment can compensate for an overly sunny or shady installation location or peculiar soil conditions.  It is suggested to set your sensor to 1/8”.  The temperature at which the freeze sensor is activated is 37°F±2° (3°C±1°) and is not adjustable. 

The placement of your rain/freeze sensor is very important.  Please consider the following to ensure that your equipment is most effective.

·      Mount the rain sensor to a gutter or roof eave where it will be exposed to direct, unobstructed rainfall (but away from sprinkler spray).

·      Mount as close as possible to the timer.  This will cause the wire run to be shorter, which minimizes the possibility of wire breaks.  Wireless rain and freeze sensors are available.

·      Mount in the highest possible position where rain will fall directly into the rain sensor without any interference from the roof or trees.

·      Refrain from mounting the rain sensor on a very sunny, southeastern end of a building as it may cause the rain sensor to dry out sooner than desired.  Similarly, mounting on the northern end of a building with constant shade may keep the rain sensor from drying soon enough.

By installing a rain/freeze sensor you will not only prevent your automatic sprinkler system from running while raining, potentially causing excessive runoff from your property, but will prevent your plants from receiving excessive amounts of water.

For further information, contact Mark Arnold, County Extension Agent-Agriculture/Natural Resources, 701 South I-35 E Service Road #3, Waxahachie, or call 972-825-5175 or email: