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).