There are a lot of Smart Home devices to buy. The most sold devices are magnetic or optical door and window switches. These devices are relatively cheap. But how is it with water alarm devices? These devices are much more expensive.

So, I ask me if it's possible to modify a Smart Home door or window switch for using it as water alarm device.

I had the following requirements:
•    Low cost project
•    Simple to build
•    Possibility to roll back the original Smart Home door switch functionality

After exploring some devices I found a simple solution to modify a Smart Home door switch for using it as water alarm device.

How to do this you can read in the attached document.