What are the logistic implications of using bottle caps as currency? I have recently been playing the game of fallout 4 and I was struck by an interesting spec of the game.

People in the nuclear post-apocalyptic world use bottle caps as barter money.

Inquiring a little, it is said that it has a certain logic to use them, since they resist more or less well the inclemencies of the climate.

They are difficult to duplicate without heavy machinery, which is scarce in the post-nuclear world.

The banks of the world are supposed to base their value on purified water and that in a certain way, if you came to a bank with 100 bottle caps you could come out with a bucket of water.

(I do not know if this means that the banks function at the same time as exchange houses and water purification and distribution facilities)

All this sounds good and in a way with some logic, but reading this only left me more doubts than answers.

How would inflation work in such an economic environment?

How can people buy expensive objects like houses or maybe vehicles, (they cost at least 10000)?

How would a bank know if another has launched a new version of purple coin that is worth more than any other single bottle cap?

If a new bottle cap of unique color appears, how to corroborate that a bank in another village supports its value? (that is, that is not false).

(Sorry about my tags I could not find some tags for a "what if" scenarios).
How would inflation work in such an economic environment?


Supposedly, whenever a wastelander opens a bottle of Nuka-Cola, "new money" is injected into the world, so that would theoretically drive up inflation, but very minimally. Also, information asymmetry would certainly cause prices to fluctuate differently in different regions of the game. I think we need to assume that banks do not communicate with each other, at least not regularly.


  How can people buy expensive objects like houses or maybe vehicles, (they cost at least 10000)?


While caps are definitely accepted as a form of currency in the Fallout world, many would opt to convert their caps to a larger capital asset that is easier to carry around. Then, the purchaser can use that to barter. It's not ideal to carry tens of thousands of caps, as you're probably implying.


  How would a bank know if another has launched a new version of purple coin that is worth more than any other single bottle cap?


The bank would probably find out when someone tries to convert the new currency for purified water or whatever the good was. My guess is that the new currency would also be commodity-backed based on something else (stimpacks, perhaps?). 


  If a new bottle cap of unique color appears, how to corroborate that a bank in another village supports its value? (that is, that is not false).


Not sure how this would work. Maybe show the bank the bottle which the cap was found on? Show that it was indeed Nuka-Cola branded. Then, the bank can take-it-or-leave-it. I'm only aware of regular Nuka-Cola and Nuka-Cola quantum, and I think they have the same cap style.