Is it legal for a person under 21 to openly carry a flask?

I'm not of legal U.S. drinking age, and I was wondering if it is illegal for a person under 21 to openly carry a flask, since a flask is widely used/created to hold distilled(alcoholic) beverages. I don't drink, nor plan to mainly because I do not appreciate the attitude people my age have towards alcohol consumption. Also I don't plan to use the flask for distilled beverages, mainly water, and or flavored drinks, I.E. Gatorade. I live out in the desert so it's nice to have a bottle of water around, but I see a belted flask as an easier way of holding liquid, rather than lugging a bottle around.