The Brita bottles were discontinued a couple of years ago. You can find them if you're lucky (my Bartell's drug store in Washington state has them), but from the posts I've read, they can cause a problem because they leak.
My solution: Ask for a large cup of ice water at any counter service restaurant. They give it to you for free. The water is from their soda fountain, so it tastes better than water from the tap, plus it's cold because it has ice. I do this instead of carrying a water bottle around - I hate heavy, clunky water bottles when you use a carry-strap, and don't like to have to carry a backpack just to have a water bottle (plus, it could leak). By asking for water when you need it, you can just drink it and throw away the cup when you're done.