Review on Protect Your Belongings with Wireless Water Leak Sensor Alarm - WER 90db Loud Buzzer, Longer Alarm Detection (Battery Not Included) by Jeremy Marshall

I didn't want to spend too much on this stuff so despite mixed reviews I went for this one. I found the alarm loud enough that I could hear it throughout the house, but the sensors are a bit specific. As previously mentioned, I would recommend placing a binder-like paper towel underneath to allow incoming water to penetrate the towel and trigger the sensor. I've tested this with and without a towel and by far the latter method is more reliable.