From The Pueblo Chieftain (David Hartkop):
Did you know, for instance, that one cup of coffee actually requires between 35-55 gallons of water to produce? So says National Geographic and a carefully compiled study by the United Nations Educational, Scientific and Cultural Organization (UNESCO)…
For it to make sense, one must track that cup of coffee all the way back to the wilds of a coffee plantation in Guatemala. Coffee is grown on trees and picked as plump red cherries. This requires varying levels of irrigation, depending on the local rainfall. Irrigating a plantation is no small business, especially considering that each coffee tree only produces one pound of coffee per year. The cherries are then picked and the seeds (what we call coffee “beans”) are extracted by pulping the fruit.
The coffee beans are then washed in clean water to remove the pulpy remnants. Washing, again, is no small process. It may take several hundred gallons to flush the pulp away from a mere 100 pounds of beans. The washed beans are then spread out to dry. When we receive coffee beans, they are dry green pellets. As dry as they may seem, each green coffee bean contains a further volume of hidden water. One hundred pounds of green coffee becomes only 88 pounds once roasted. The 12 percent loss in weight is actually due to water released as steam from the beans during the roasting process.
More Colorado Water 2012 coverage here.