"Bottled or tap?" is the first thing we're asked in restaurants, a practice I find most irritating. The bottled water option seemed to coincide with the "paper or plastic" choice at the supermarket. Both questions force us to reveal our values to people we don't really know. Tap=cheap just as plastic=not ecologically aware. To be seen as people of valor requires ordering pricey bottled water (except in vegan restaurants that recognize transporting water is environmentally unfriendly) and producing our own reusable shopping bags.
Because of rising food costs and the weakened economy, restaurants are in trouble (except those with star chefs that can't give you a table the same year you call). Customers are eating out less frequently, ordering cheaper items and sharing. Restaurants are, therefore, reducing portion sizes, switching to cheaper ingredients, buying smaller plates. Ground chuck is the new kobe beef; liver is the new foie gras. Watered down drinks are the new drinks.
A restaurant that uses a professional menu designer will place its most profitable dish third on the list as that's proven to be the most frequently ordered item. My hunch is it'll be bottled water.