I have heard estimates as high as 37 gallons (140 liters) of water used in the production in each cup of coffee. As someone who is an inveterate drinker of coffee for multiple reasons (caffeine, calming effect of sipping at it while coding, the extra exercise from getting up and walking over to grab another cup every 40 minutes or so), I can't really go entirely without, but I'd like to do something a bit more sustainable. It looks like tea is a bit better at about 9 gallons per cup (35 liters). In either case, I'm sure that I'm expending some amount of resources getting the water heated as well.
I'm moving to refilling my water bottle at work for about half of my consumption, but water doesn't entirely cut it, between the lack of caffeine and that it seems to be worse for forcing me off to the bathroom to dispose of excess in my system. What sort of a substitute can I use?