[Diana in Wisconsin]

Thanks! Something to consider! Fancy!

All of our well taps (three in the house yard, one in the pasture) have handles that can accommodate a padlock if need be. For now, those are unlocked because we have workers through here planting and/or harvesting and sometimes they need a drink or water too cool something down.

I don’t have the rain barrel locked, but that’s usually got bugs and other ‘interesting’ things in it (even though it’s screened on top where the roof water is channeled) and that water needs to be strained and boiled before drinking. LAST resort. ;)

The idea of a ‘key’ that fits them all is very smart.

[Iron Munro]

The "handle-less" keyed faucets would be ideal for your application.
Much simpler than padlocks and still secure.

They come with a specific key from the manufacturer as in the picture below.
As you might expect, those keys are sometimes lost or misplaced.
I have seen places where people forget and leave them on the faucets only to find them gone.

As I described in my earlier text, the 4-Way Key is a universal tool that fits a variety of different faucets.
It's always wise to have a backup or two.