Don't think 64oz, think one bottle at a time.
I can chug a 20oz bottle in just a few minutes if it's room temperature(slightly cool), which I do about an hour after breakfast. Then I have an ice cold bottle with other meals, and another to sip at while I'm on the computer, or watching TV. To keep track, I place the empty bottles on the kitchen counter - before I know it, there are 3-4 bottles there, waiting to be refilled for the next day.
(I bought 4 reusable water bottles.)