Why no bottled water? There are parts of this country where the tap water is barely drinkable. (Florida, for example - beyond hard water)
Instead of bottled water (which is $5 a case) maybe focus on the type of beef, chicken and fish people can buy? (Regular ground beef vs wagu ground beef, salmon vs lobster, etc).
The main reason they don't restrict them as much as some think they should is because they basically qualify for a "certain amount of money" so if they decide to blow 90% of it on junk, steaks and lobster, then are forced to eat ramen noodles the rest of the month, after the good stuff runs out, that's on them. But if they're smart with it, they can eat well for the entire month.