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A Better Lawn on Less Water

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Irrigation Shut-off Devices

Irrigation shut-off devices (either rain sensors or soil-moisture sensors) have been required by Florida law on all irrigation systems installed since 1991. Some counties require them on all automatic irrigation systems, regardless of when they were installed. They are inexpensive and can save a lot of water. Be sure you purchase one and install it as part of your irrigation system if it’s not already included. Usually it is sold separately from the controller.

If you are using a rain sensor, which are more common than soil-moisture sensors for home-lawn irrigation systems, it should be positioned on the roof or rain gutter with open sky above it. It is wired into the controller and will interrupt scheduled irrigation if sufficient ran falls. It will also keep the system turned off for a preset "dry down" time in which no irrigation is applied.

Adjust and Maintain Your Rain Sensor

Set the sensor to stop operation after 1/2–3/4 inches of rain has fallen. Fully open the "dry down" vent to prevent the system coming on again quickly. The "dry down" time is how long the system stays off once the rain sensor has interrupted irrigation. Your sensor’s instruction sheet will give details on how to make these settings.

Make sure your sensor is operating properly by checking it every month during the rainy summer season and quarterly the rest of the year. A simple method for checking is to pour or spray a small amount of water over the rain sensor while the irrigation system is operating. Irrigation in all zones should stop soon thereafter and remain off for at least a couple of days.

The controller panel may appear to still be on and operating, in spite of the overriding action of the rain sensor switch. Some controllers have a corresponding "on-off" rain switch control on the panel. On these models, the control should be set to activate the rain sensor. For more information, see "Residential Irrigation System Rainfall Shutoff Devices."


Using the Irrigation System for a Better Lawn on Less Water

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