Source: City of Santa Barbara
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
Free! Doesn’t cost anyone anything! No taxes or grants or donations from billionaires were used to pay for these! Maybe they are magical devices?