A Money Reservoir - A different kind of banking

Imagine there was a big reservoir full of money that doesn't belong to any one person. Its the property of a whole community.
And there is a community rule that a person is allowed to take money out of the reservoir as long as, just as with a private bank, they pay it back within a certain time period with interest.
Like a reservoir of water that serves a community, if people keep paying back the money they take from the reservoir with interest that means there will always be money for community members to borrow.
In otherwords its like a bank/building society that is owned by a community rather than by bankers.

What about security? - Well it could be like a club that you have to become a member of to use and enrolling for membership would involve background security checks.

And who would supervise all this money? - A community could elect trusted community members to be reservoir managers.