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?
When I was in Thailand, at a reasonably nice hotel in Bangkhok, when we ordered water the water "opened our bottles for us" - I immediately sent them back for unopened bottles. My friends thought I was a little paranoid, but we were all cautious about the water, so not that big a deal.
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.
Carbonated drinks are also safe - the acid kills pathogens.
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.
