Stormin Mormon wrote:

While building a new house some 10 years ago and seeing a long pipe
run between the kitchen and bathroom, I installed two 50 gallon
highly-insulated water heaters at the two water-using locations to
keep the hot water runs short. One is upstairs.

If the city water fails, I have 100 gallons of drinkable water just by
shutting off the main house valve and opening an upstairs sink valve
so that air and gravity can do their thing. I've been thinking about
adding a tire valve fitting to the tank upstairs so that I could use
a hand tire pump to add some pressure to the system. Fortunately,
there's been only one water failure since installation, but that was
enough to show that the system worked.


But it's not drinkable, or, at least should be viewed with suspicion.

The water in a hot water tank is often filled with double-nasty bacteria.
Many Legionnires Disease outbreaks have been traced to the washing of
vegetables with water from a hot water source.

Hot water is to be used for washing, not consuming. Unless you boil it
first, but in an emergency, boiling water may prove problematic.