About water consumption: depending on your make of water meter, there's often a small reflective wheel that turns eg. once for every liter. Sometimes these are made out of metal or even slightly magnetic. An arduino with an optical or Hall effect sensor might get you real far in real time, high resolution data collection!
Alternatively I've had success in wiring up a temperature probe directly to the incoming water line, and comparing that temperature to the ambient temperature. Where I live that works because the water arrives from underground & is always much cooler than ambient air. The time-integrated difference between the two is a proxy for how much water you use... this is much more involved to get meaningful data from, tho.
On mobile so hard to link, but memory says OpenEnergyMonitor's docs site on pulse counters has a computer vision approach too. Think it reads the numbers from the display.
Alternatively I've had success in wiring up a temperature probe directly to the incoming water line, and comparing that temperature to the ambient temperature. Where I live that works because the water arrives from underground & is always much cooler than ambient air. The time-integrated difference between the two is a proxy for how much water you use... this is much more involved to get meaningful data from, tho.
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Edit: a proximity sensor that detects metal might be the most straightforward thing, if you have a water meter with a rotating metal gauge https://www.alldatasheet.com/view.jsp?Searchword=LJ12A3-4-Z/...