Water damage ranks among the costliest home repair issues—one small leak can ruin floors, cabinets, and hidden infrastructure. Enter Shelly’s Flood S Gen4, a leak detection sensor priced under $30 that promises Matter certification and native Apple Home support straight out of the box.
Design Built for Early Detection
Rather than relying on the usual tiny metal probes that need precise contact with water, the Flood S Gen4 spreads its sensing across three large stainless steel pads on its base. This design allows it to detect even minimal amounts of clean or low-conductivity water—think AC condensate—so it triggers faster in areas high on risk like beneath sinks, behind toilets, or under water heaters. Its slim profile makes it easy to install in tight, often-neglected spots.
Connectivity, Modes & Alerts
Connectivity is broad: the Flood S Gen4 supports Matter, Wi-Fi, and Zigbee. It’s compatible with Apple Home as well as ecosystems such as Google Home, Amazon Alexa, SmartThings, and Home Assistant. Once added to Apple Home, automation is possible—for example, cutting off power via a smart plug when a leak is detected, flashing lights, or sending leak notifications to your iPhone.
The device includes a local alarm in addition to mobile alerts. Users also get two detection modes—”flood” and “rain”—and three sensitivity profiles: intense, normal, and economic. The economic mode trades speed for battery life, with the CR123A battery rated to last up to two years under typical usage.
Value and Use Case
At under $30, it’s an easy buy—and one you’ll want multiples of: under the kitchen sink, beside the washer, near the dishwasher, and in front of the water heater are all suggested locations. Since it plugs into Apple Home via Matter, automations and alerts become accessible without jumping through hoops. It’s hard to find faults here—this is a smart purchase for any comprehensive smart home setup.
What to watch: battery life in real use, long-term reliability of the aluminum pads, and how seamless Matter integration stays as Apple and other platforms continue to evolve. If Shelly delivers, the Flood S Gen4 could set a new bar for affordable leak detection in smart homes.
