If you're in a rich area in the US, look for Spindrift soda -- the brand started out in Boston, but has spread to other upper-class milieus since then. There's

If you're in a rich area in the US, look for Spindrift soda -- the brand started out in Boston, but has spread to other upper-class milieus since then. There's also La Croix, as mentioned by another poster here -- it's artificially flavored, I think, but still pretty good and definitely low on sugar. (Spindrifts are made with fruit and soda water; they're not low-sugar or sugar-free, but they haven't been sweetened out the wazoo like Coca-Cola.)