On: Humans are more dependent on water than many other...

[bombcar]

And why you may not want to flush if the water goes out - the toilet tank is potable if sometimes a bit slimy.

There’s also the water heater if it has a tank - it can be drained from the bottom (you’ll want to shut it off if it’s not refilling).

[thehappypm → bombcar]

The water heater tank is a good suggestion!

[Filligree → thehappypm]

It's generally recommended not to do so. But if it's either that, or dehydration...