The simplest function of the system is also one of my favorites. It automatically refills the water tank of my coffee maker. All it needs is a float switch and a solenoid valve that lets fresh tap water flow in the tank.

Thanks to the SCADA like the design of my smart home system it is easy to derive the water usage from the time the valve was open (@ Level 3/4: A Raspberry PI With Node-RED and Grafana). 

Every step up on the following graph represents a refill of the tank.

Don't worry there are some safety functions implemented in Level 2: (A Raspberry PI with CodeSys software PLC ) of the system. Such as maximum filling time or only refill when someone is at home.

And it is possible to trace all actions within Grafana: