It's customary in American restaurants to maintain a glass if iced water at the table. The practice is so often considered de rigeur that often tourists in Europe complain about not being able to get ice with their meals. I find, however, that drinking very cold water (and often these glasses are more ice than water - which then necessitates the provision of plastic straws to prevent spillage while drinking) tends to mute one's taste buds. Thus, I prefer un-iced water in restaurants.
And I must give kudos to the Black Bottle restaurant in Seattle for keeping this practice. It's ostensibly a wine bar but serves a tapas style menu of foods. Not all the items are knockouts (for example, they could do better pita bread to accompany the garlicky hummus) but it's fun. And you keep your sense of taste.