Alright, how about this? Soup IS drinkable, but it's just water combined with juice from your choice of food. Soup is mostly drunk, unless there is something else inside the bowl which you have to eat to finish drinking your soup. Besides, if you were to drink soup the entire time, I don't really know what would happen to your body (except make you feel a little warm). Anyway, I believe soup can be considered a drink, but it can't really replace water and milk as a whole.