Water damage is one of those problems that’s silent until it’s catastrophic. The MOBI Wi-Fi Leak Alert Sensor is a small, battery-powered puck that lives near your water heater, under the sink, or beside your washing machine. It connects directly to your home’s 2.4 GHz Wi-Fi network and sends an alert to your phone the moment its metal probes detect moisture. No hub required. No monthly fees. Just two included AAA batteries and a strip of adhesive tape to keep it in place.

The sensor’s detection range is 48 inches, which means it’s best placed directly in a spill zone rather than across the room. When it senses water, the app notification arrives within seconds. That speed matters. A slow drip from a supply line can ruin flooring in hours. The MOBI sensor gives you time to act before the damage spreads. The app is straightforward: you get an alert, you go fix the leak, you dry the sensor and put it back. It works reliably in our testing, with no false alarms from condensation or humidity.

One honest limitation: the sensor relies on 2.4 GHz Wi-Fi only. If your router is far from the sensor’s location, signal strength can be spotty. The adhesive tape is functional but not industrial-strength. For high-humidity areas like a basement crawlspace, you may want to add your own mounting solution. For the price, this is a practical, no-nonsense early warning system. It won’t stop the leak, but it will tell you about it before the floorboards warp.