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Free Rain Shut-off SensorsWater

A rain sensor is an irrigation shutoff device that prevents an automatic sprinkler system from turning on during and after a rain storm. Rain shut-off sensors are wired to an irrigation system controller and override the scheduled irrigation when a sensor on the shutoff device detects water.

When the collected rainwater has evaporated from the sensor, scheduled irrigations resume. Rain shut-off sensors are simple, economical and useful tools for preventing irrigation that would be wasteful. Rain shut-off sensors work best for short off periods. For extended periods, it is more accurate to have sprinkler timer in the "off" position.

City water customers can get a rain shut-off sensor for free when they get a free Water Checkup. Call the Water Conservation Hotline at (805) 564–5460 to schedule a free checkup at your home or business and receive a free rain sensor!

Video: How to Install a Rain Shut-Off Sensor

Rain Shut-off Sensor FAQs

What is the ideal installation location for a rain shut-off sensor?

The device should be mounted in an open area outdoors where it will be exposed to unobstructed rainfall, but not in the path of sprinkler spray. It is typically installed near the roof line on the side of a building so that trees, overhangs and awnings are not blocking direct rainfall onto the rain shut-off sensor.

Check orientation of sensor when attaching the bracket. Avoid mounting the sensor in a sunny, southern end of a building because it may cause the water in the sensor to dry out sooner than desired. Similarly, mounting on the northern end of a building with constant shade may keep the sensor from drying soon enough.

The closer the rain switch is to the controller, the shorter the wire run will be. This will also reduce the chance for wire breaks. Wires from the rain sensor attach to an indicated wire terminal in your irrigation controller.

Will a rain shut-off sensor affect the schedule of my automatic timer?

No. The rain sensor merely overrides the cycle until the rain sensor's disks or water collection dish dry out. The irrigation system's timer will then come back online to the regular irrigation schedule. The rain sensor should be set to shut off the system when up to 1/4" of rainfall has occurred.

Who can install rain shut-off sensors?

Rain sensors can be installed by homeowners or irrigation professionals.

What are the advantages of having a rain shut-off sensor?

  • Saves You Money — Reduces your utility bill by overriding your     irrigation system after adequate rainfall has been received.
  • Saves Your System — Reduces wear on your irrigation system because the system runs only when necessary.
  • Protects Your Landscaping — from too much watering.
  • Conserves Water — Rainfall is used to water your lawn instead of fresh drinking water.
  • Conserves Community Resources — Using less water also extends the life of the water treatment plant (if you use a municipal water system).

How long will the system stay off after it rains?

This depends on many variables and is hard to accurately predict. The relationship between the rain sensor set point and how much it actually rains is the first variable. The longer it rains past the set point (up to one inch) the longer the system will stay off. Next, all the variables of the weather will determine how fast the water dries out: wind, sunlight and humidity all play a roll. In practice, all these variables usually result in the sensor shutting the system off a minimum of a few hours to a maximum of three - four days.

After it rains, sprinklers stay off too long. What is wrong?

  • In humid areas, make sure the device receives direct sunlight to ensure evaporation.
  • Make sure sprinkler water doesn't reach the device.
  • Check for unwanted runoff from roof, trees or plants.

How long do the disks last?

At least ten years! There are working models that have been fully exposed to the elements for more than thirteen years and are still working fine.

Will I lose my controller settings if the rain shut-off sensor shuts my system off due to rain?

No, the sensor acts as a switch to break the circuit to the solenoid valves of the irrigation system when it has rained. This allows the timer to advance as scheduled, but keeps the valves from opening the water flow. Once the water has dried sufficiently, the switch closes again to allow for normal operation.

When do I turn my controller to “rain off”?

It is recommended that you turn the sprinkler timer to "rain off" for extended wet periods during the rainy season. Rain sensors work best for short off periods. For extended periods, it is more accurate to have irrigation controller in the "off" position."

Last Updated: Apr 11, 2014