Couldn't one just pop open a bottle, freeze some ice cubes, tell your customers you are using "ice made from brand of water" and ignore the expensive, prepackaged option from the supplier?
I killed myself laughing when I saw the same scam being pulled by one of the characters in Slum Dog Millionaire.
In other words - if it doesn't come with a factory seal, presume that it's not factory fresh.
In areas that don't have bottled water from a brand I recognize, I drink nothing but fermented beverages (I've brushed my teeth with beer).
I'd use brand-name ice cubes, if they were packaged in a known, trustworthy manner.
You can also easily carry water purification stuff - a bottle of polarpure lasts many many uses, and there are stirring wands that use UV light to kill germs. You may need to do a bit of research about what kills what, though.
What acid? There's no hydrogen in CO2.
I rememeber one of our party trying to order a Margarita with no ice in a restaurant in Zambia once.