The Good: D-Link's Water Sensor is smartly designed and features all the important perks to make it an effective flood detector. The Bad: D-Link's only real weakness is that it relies on being plugged in, which means power outages are its Achilles' heel. The Bottom Line: The D-Link Water Sensor is one of the best flood sensors on the market. If you're considering buying such a device, this should be the first option on your list -- especially if you don't already use a smart-home hub. The design behind leak sensors is actually pretty cool: essentially, most sensors have two or three metal probes that, when they come in contact with water, detect increased conductivity and set off an alarm. It's an elegant solution to the age-old problem of flooding.But D-Link takes an even more creative approach. Rather than using probes, D-Link's Wi-Fi Water Sensor uses a cable with long, twisting leads embedded in it. You can run the cable along the edge of your basement floor, say, and if water touches it anywhere, the twisted leads detect increased conductivity and set off an alarm. It's a little like what we did when last winter.D-Link is unique for more reasons than the cable, though. The base unit also plugs directly into a wall, negating the need for batteries, and connects via Wi-Fi to your phone -- cutting out the hub middleman that limits so many other .The result is a solid product with a slightly higher price of $60 (compared with its $40 competitors that work with SmartThings or Wink).