There's nothing like a Slurpee or Icee slush to cool you off on a hot summer day... Unless you don't want to load up on sugar.
Think about it, what is the world's most popular beverage? No. It's not Coca Cola... it's WATER, so why not make the world's most popular iced beverage in the world's most popular flavor?
The great thing about a plain water Slurpee is that it not only goes down colder, but it stays colder longer than water alone. So, if you are one of the millions of people who prefer water to a sugared beverage, it's about time you should be able to enjoy a cool Slurpee too.
If nothing else, start it off plain... and let people add just a bit of fruit juice or a dash of flavor... just like a roadside snow cone vendor.