I think it's only a matter of time before restaurants start charging for water (even tap), or just offering bottled (for a charge) to customers. Not saying much, maybe .50 or so for tap, but I think it's just going to take one major restaurant to do it before it takes on. Restaurants make most their profit of beverages, people drinking water lowers the profit of the business. Not saying I disagree with anyone ordering water to save a couple bucks, but it's bad for the business.
I don't think adding something to the water is all that bad, although I do think it's a bit tacky. The one thing that gets me, is the people that order water and say they want extra lemons. Then they sit there, squeeze the lemons, and add sugar. Now that's just being flashy cheap, and a server seeing this isn't going to pay as much attention to you as the table that has drinks/appetizers.