The portable carts don't have ice water, but the permanent ones do. Any place that has fountain drinks will give you free ice water in a regular cup like you'd get a Coke in. Depending on where you go, the sizes might vary. I know the place in MGM (oh sorry, Disney's Hollywood Studios) just inside the entrance to the right gives HUGE cups of ice water - so nice to stop on your way in/out of the park and grab a couple!