Smart leak detectors are small gadgets that alert you whenever it finds water in places you want it to be - basement, around the refrigerator, the washing machine, sinks, and toilets. 

Some smart water sensors work alone via Wi-Fi. Other water senros link to a smart-home hub using wireless technologies such as Z-Wave or ZigBee. 

When they sense water, smart water sensors can send you a message on your smartphone.

Good smart leak detectors can work with your existing wi-fi network. The best ones can be managed without you needing a central hub.

The best smart water leak sensor: D-Link DCH-S160 Wi-Fi Water Sensor (works with existing wi-fi, IFTTT, and other D-Link devices)

The second best water leak sensor: Fibaro Flood Sensor (with Z-Wave and a smart-home hub)