Water Process

The process is similar to the indirect solvent process, with a few twists. First, activated charcoal, rather than solvents, removes the caffeine from the water. Second, rather than recombining the water with the beans, the first batch of beans is thrown out and the water is combined with a new, untreated batch of beans. The theory behind this is that since the water is already saturated with every dissolvable compound except for caffeine, only the caffeine in the beans will dissolve, leaving the flavor intact. Since the water is used over and over, some flavors may become commingled between batches.

The most well known variant is the Swiss Water Process, the first economically viable water decaffeination process and the current industry leader. The company asserts that it has made substantial improvements to reduce the cross-batch contamination phenomena, to the point where they are not an issue.