homeassistant

What are you, a data center?

Lots of good suggestions here, I'll also thrown in that a basic standalone automation can help prevent the worst also:

if valve not "closed" for > 45min
  set valve "closed"

Edit: use not closed instead of open to prevent brief unavailable states from messing with it.

To prevent things like this from happening, you can create alarms in Grafana to notify you of unusual behaviour. Something along the lines of "If water consumption in the last 6 hours is > 10L / hour, fire the alarm and notify me".

I like to think of stuff like that as an error culture: errors are bound to happen, be it a wrong Whisper transcript, a broken pipe, etc, and that's okay. You can't never be fully sure you are error-free. What you can do is create a culture that can catch these errors in their early stages, without having to wait, say, a whole month for the water bill to be astronomically expensive for you to say "Hey, something's wrong" (that wasn't the case here, but bear with me).