What Makes a Leak Detector Smart? How Much Does a Water Leak Detector Cost? Compare Specs: Our Picks Side by Side If you’ve ever come home to a soggy basement or found out too late that your kitchen sink or toilet has a slow leak, you know how expensive it can be to repair or replace carpets, flooring, and walls that have sustained water damage. Finding leaks before they can do major damage is now easier than ever thanks to the proliferation of smart home water-sensing devices that send alerts to your phone when they detect moisture. They range in complexity from simple puck-shaped sensors that you place on the floor, to in-line systems that monitor your water flow rate for irregularities that may indicate leakage.