References

https://gaggiuino.github.io/#/?id=home 

Has water sensor, scale built into drip tray.

Check tank water level

https://gaggiuino.github.io/#/accessories/tofnled 

NCP5623

or

PCA9632

https://www.instructables.com/Espresso-Ultrasonic-Water-level-Sensor-UWS/   uses SRF05 (best) ultrasonic sensor

https://www.itcamefromtheworkshop.com/2014/08/upgrade-to-low-water-sensor-for.html   uses tilt sensor

https://www.amazon.com/Non-Contact-XKC-Y25-NPN-Intelligent-Sensitivity-Non-metallic/dp/B07NKHT9NS   liquid level sensor

https://randomnerdtutorials.com/esp32-hc-sr04-ultrasonic-arduino/    Using ESP32 and sr04 ultrasonic distance sensor

HY-SRF05 

Use code from rnt link to implement

Connected to webserver esp32 because it was easier