Good House Keeping - BEST LEAK DETECTOR WITH MULTIPLE ALERT CONTACTS

https://www.goodhousekeeping.com/home-products/g32318103/best-smart-water-leak-detectors/

The SimpleSENCE detector can be placed where leaks tend to happen – for example, under a sink or by a leaky window. Its wrap-around sensor detects leaks and freezing temperatures, triggering an alarm. Easy to set up with the app, you can customize alerts on your phone, and set up alerts to go to numerous contacts you choose to help you manage a leak and/or turn off the water supply, e.g., if it's in your summer home, or you're away on vacation. Multiple units can be paired with the app with their location noted, making it easy for you to identify the source of the alarm. 

The SimpleSENCE detector shows battery level and WiFi strength which is handy when you're choosing a location for the sensor. The unit doesn’t need a hub, and doesn't integrate with any smart home devices. One tester reported he was “super happy” with the unit, and that it gives him “peace of mind” after it alerted him to a minor leak he could quickly fix before it caused any damage. Be aware that it does not measure humidity levels.