Heater / Air Conditioner Water Level Tank alarm

I have a condensation heater boiler and some air conditioner units, despite their announced energy efficency they drip condensated water outside throught the drain pipe (as expected).It’s a remote monitoring but this is a very simple task.
I made a bit of research and i found a Zigbee battery powered water leak sensor (with external probes) and a small (no powered) floating switch. Replacing the contact sensor with the switch i’am able to trigger an alarm, in my case a notification and voice announcement, on Alexa Echo dot.

Parts List


1. Optionally start pairing the sensor with your zigbee coordinator and add it to Home Assistant or Zigbee2Mqtt (i use the Sonoff Dongle but it’s indifferent, you can also test if shorting the probes marks the sensor as closed/open. The sensor is pretty reactive!

2. I opened the sensor case and located the probes pads

3. Desoldered the original leads and replaced with the floating switch cables. I little trick is to reverse the “ball” if necessary so it triggers closed (wet) when it’s in up position.

4. Insert batteries and close the plastic case. Done.

Mouting outside

My water tank is a big bottle so i found a L shaped plastic bracket. I screwed the floating switch and enclosed the sensor inside a plastic bag to ensure light rain proof for the sensor case.

Final toughts

You can use any custom card you want in Home assistant

I integrated into my alarm sistem automation but you can also trigger Alexa / Google home voice announcements (https://community.home-assistant.io/t/alexa-media-player-integration/352985/3) calling its service via a simpler automation.

Total cost about 10€ (~11$)