A good smart home water metering system is an analog coupled system. Connected directly each water consumption endpoint is an analog pressure meter with an analog electrical hookup for smart monitoring. There can also be a similar analog flow meter. Earlier I wrote about using sound metering as a cheap way to monitor for events such as when water faucets are running. Why doesn’t sound metering work? It can get false positives if someone is watching a video on a smartphone with the sound of running water, nearby the faucets.
For the flow meter. The flow meter can have an electrical output where dynamo energy is generated. Well, I should put it as that is how the flow meter monitoring works!