I don't mind if the water isn't icy cold. If it's that hot out, you won't be carrying around a full bottle for long anway.
We are used to drinking bottled water and don't consider it an unnecessary or extra expense--I would rather buy water than drink soda or juices all day for the same $. We prefer water.
We always buy the bottles of water as we go along. I drink pretty much the entire bottle as soon as I buy it, then just buy another when I am thirsty again. Of course, sometimes dh and dd help me out and we all "share" a bottle so it's easy to drink the whole thing, but I know that not everyone would be comfortable with that.