I use an Imago which I like very much. If I ever get an alternate bag it will probably be a Cafe Bag. But lately I've started carrying a water bottle and it is awkward to find a place for it. I could pack it inside the Imago but condensate or spillage could wreak havoc with my notebooks and electronics. I'd feel more comfortable if I could get a waterproof pouch to hold the water bottle and secure it so that it is upright.
Any suggestions for a pouch like this - or a way to fix it to the inside of my bag?
By the way I know that that some of the backpacks have better provisions for water bottles, but I do not want a backpack. Aesthetically I am very fond of the messenger bag style.