The ability to shift click a jug to empty the fluid inside of it similar to emptying a wooden bucket would be nice, good way to remove accidentally collected salt water.
Configurable "on vs off" option, ideally.

It would be better if we can boil them out. Heat in a firepit/forge and at some point it swaps the filled jug with an empty one.

Yay, thanks @alcatrazEscapee