Silvia’s water tank needs to be filled every 2-3 uses especially if you follow the temperature surf and cooling flush procedure. With a PID, water consumption is reduced but still, you need to check and fill the tank quite often. Some sort of water level indicator was needed. Water level sensor and a kind of visual indication was the solution.

Searching the net lead me to a very cheap floating sensor and adding a LED to it was straightforward.
I of course, placed the LED in the external box where all controllers were located.

The LED I chose was a flashing LED , a led that has 2 built-in LEDs with an integrated circuit that makes the flashing between the blue and red internal LEDs.

 Tip: Make sure to add a relevant resistor to the LED according to its spec.
remember:
R Ohm = (Vs – VL) / I 
Vs= supply Voltage (=12v in my design)
VL= LED V (Forward voltage)
I= LED current in A

 Tip: Anode (+) leg of LED is the longer leg of the LED.

This sensor is actually a switch and adding a LED to it required a low voltage power source.
Seeing the advantages of using 12V for few mods, I have decided to add a 12V power supply.
This opened new possibilities like the following light mod and some new alternatives for the brew/steam mods above.

Attaching this sensor to the tank while allowing disconnecting it (for cleaning purposes) was an innovative process.
The solution can be seen in the images. This solution involves a plastic pipe that has a thread on one side that attaches to the sensor and seals its wires output and on the other side, it clips to a standard clip that is connected to the tank.
Pipe length is such that its upper end is above water level. The pipe and sensor assembly can easily be removed to allow smooth removal of the water tank for cleaning and maintenance.

 Tip: If more attention is needed to low water level alert, a 12V buzzer can be added to this installation. Its size is very small and it cost few cents.