There's a good deal of variation. Without digging into how that figure was produced, it could be worthwhile to mention that the production process Jay Ruskey sa

There's a good deal of variation. Without digging into how that figure was produced, it could be worthwhile to mention that the production process Jay Ruskey says he's interested in cuts a lot of water out of the process. Once coffee cherries are picked, getting down to the seed inside (aka "coffee bean") can happen one of roughly three ways: "natural process", letting the coffee fruit dry out like a raisin on the seed; soaking/fermentation, letting the coffee soak in water for 24-48 hours once (or often twice in Kenya); mechanical demucilagation, separating the seeds from the rest with a machine. The demucilager is common in Costa Rica. I can dig up some more material later, but the government in Costa Rica is strict about water waste, essentially requiring farmers use demucilagers to process their coffee. I don't know how much this would affect the water involved in coffee production, but I would guess it would drop the amount necessary for production in cases like Ruskey's.