Rain Sensors and Rain Shutoff Devices Explained
There's nothing more wasteful — or more obvious — than sprinklers running in the rain. A rain sensor prevents exactly that, automatically pausing your system when it rains. It's an inexpensive device that saves water and often is required. Here's how rain sensors work.
How a rain sensor works
A rain sensor detects rainfall and interrupts the signal from your controller to the valves, pausing watering until things dry out. Most use a stack of moisture-absorbing discs that swell when wet to open the circuit, then shrink as they dry to resume normal operation. It works with most standard controllers.
Why it matters in SoCal
While our region is dry much of the year, winter and occasional storms can dump enough rain that watering is wasteful — and many water agencies require rain sensors or rain-shutoff capability on irrigation systems. A sensor ensures you're not watering during or right after rain, saving water and keeping you compliant.
Rain sensors vs. smart controllers
A basic rain sensor handles rain shutoff. A smart, weather-based controller goes further — adjusting all watering to forecasts, temperature, and season automatically. Many smart controllers use online weather data for rain skipping, while a physical sensor reacts to actual rainfall at your home. Either is a worthwhile upgrade; together they're ideal.
Installation and placement
Mount the sensor where it's exposed to open sky and rain — not under eaves or trees — and wire it into the controller's sensor terminals. It's a quick, low-cost upgrade. Our irrigation team can add one to your system.
Frequently asked questions
Do I need a rain sensor in Southern California?
Many water agencies require rain shutoff capability, and a sensor prevents wasteful watering during storms — so yes, it's worthwhile.
Do rain sensors work with any controller?
Most standard controllers have terminals for a wired rain sensor; many smart controllers include rain-skip features using online weather data.
Arbol Roble has cared for Inland Empire landscapes since 1997, serving Rancho Cucamonga, Ontario, Fontana, Eastvale, Corona and Riverside. Request a free quote or browse our residential and commercial services.
About the Author
The Arbol Roble team are licensed landscaping and irrigation professionals (CSLB License #1077455) serving Rancho Cucamonga, Ontario, Fontana, Eastvale, Corona, Riverside, and the greater Inland Empire.