Shelly Flood Gen4 Review: Smart, Expandable, And Budget-Friendly Leak Detection

The Shelly Flood Gen4 Gen4 has an off-white rectangular enclosure with an IP44 waterproof rating, measuring 3.8 by 2.9 by 0.9 inches (HWD) and weighing 6.5 ounces with the batteries installed. It comes with four AA batteries that are rated to last up to two years before needing to be replaced. Also included are mounting screws, a 3.2-foot cable that connects the sensor to a 6.5-foot leak-sensing cord, an adhesive mounting pad, and a quick-start guide. If you have more space to monitor, you can pick up additional sensing cables and daisy-chain them for up to 490 feet of coverage.

(Credit: John R. Delaney)

On the front of the sensor, you’ll find an LED button that serves several functions. Tap it once to send the current sensor status to the mobile app, twice to put the sensor to sleep, three times to enter Zigbee mode, and five times to toggle back to the default Matter mode. You can press and hold the button for five seconds to reset network settings, and for 10 seconds to restore the sensor to its factory settings.

The LED turns blue when the sensor is ready for pairing, red when it’s disconnected from the network, or yellow when it’s connected to the network but disconnected from the cloud. When the sensor is connected to both, the LED turns green before going dark.

On the bottom edge of the Gen4, you’ll find a port for the 3.2-foot connector cable; around back is a removable mounting plate for installing the sensor on a wall. You can access the battery compartment by prying the sensor open with a flathead screwdriver.

The sensor offers Flood Detection and Rain Detection modes. You use Flood mode to monitor common sources of leaks, like a washing machine or pipes under the sink; Rain, meanwhile, lets you automate outdoor devices such as automatic awnings and sprinkler systems. Flood mode also offers three alarm settings that change how the built-in buzzer performs. In Intense mode, it sounds continuously for 10 minutes, then for one minute every five minutes; in the default Normal mode, it sounds continuously for five minutes, then for one minute every half hour. Economic mode disables the buzzer, but the sensor still sends you push and email alerts.

If you want a sensor that can pair with a water shutoff valve, consider the First Alert L1 ($69.95). It costs more than twice as much as the Shelly Flood Gen4, but it can be paired with a Resideo (sold separately for around $200) to automatically shut off the water in your home when a leak is detected. The Flo by Moen ($49.99) is another model with this feature, but its companion water shutoff valve is more expensive at around $500.