What I have wondered about is something plain and simple:
Canned water. Yes, cans are not perfect, but they are completely recyclable, and can store water indefinitely. Pretty much what Anheuser Busch did for a day for Texas flood victims, but a constant product .
Costs per item would be cheaper than soda water, as all that is needed is filtered tap water.
For an added bonus, add a 5-10 cent deposit onto each can. That will pretty much ensure they come back.
: One could always make a joke about it not being a change from their beers, but what they did was a good thing, regardless.