What irks me the most are the restaurants and bars that have caught on to the bottled water craze. I've been to some that won't give you a glass of ice water, you have to buy a bottle of water. That pisses me off.
EDIT: Oh, and I use a PUR filter on my tap at home, not because the tap water is nasty in New Orleans, but because we have corroded plumbing. I drink straight tap water at my parents' and other's homes.