SwitchBot Water Leak Detector for $19: This rectangular detector triggered swift alerts in all my tests with a 100-decibel alarm. Aqara Water Leak Sensor for $19: This Zigbee sensor is best used with Apple’s HomeKit, and you need an Aqara hub (sold separately). Stitch by Monoprice Water Leak Sensor for $25: This affordable water leak detector has a design that’s similar to our top pick. Leak Detectors to AvoidWe did not have a great experience with every water leak detector we tested. Swann Leak Alert Sensor for $16: While this battery-powered water detector (two AAAs) is affordable, I had a terrible time setting it up.