I know there are washing machines on the market that currently sense if there is water coming into the unit and will produce an error if no water is detected.

With the number of sensors and such now a days I’m sure there’s a way manufacturers could put sensors into these devices and when the machine gets installed requires you to go through a setup which will run a pressure test so it knows how much water/gas pressure is getting to the unit. Should this pressure be reduced by a certain percentage (say 5% for a washing machine, to account for pressure changes when the showers on dishwashers running and toilet gets flushed) the machine turns off, triggers the alarm and triggers the automation system to close the valve/s. Could get to the point where it’s smart enough to know whether it’s the hot or cold water and only closes that specific valve.