In the 1980s the Swiss firm Coffex S.A. developed a commercially viable decaffeination process using water only — no solvents whatsoever. As in the indirect solvent or solvent/water process described earlier, the various chemical constituents of the green coffee, including the caffeine, are first removed by soaking the beans in very hot water.
In the Swiss Water Process, however, the water is stripped of its caffeine, not by a solvent, but by percolation through activated charcoal. (It really ought to be called the Swiss Charcoal Process.) The beans are returned to the hot water, where they reabsorb the remaining, caffeine-free flavor constituents from the water.
This process is more costly than the solvent process because the separated caffeine cannot be recovered from the charcoal and sold separately, as it is with the two solvent methods. It is also controversial in terms of flavor. Many coffee professionals contend that the Swiss Water Process blurs flavor more than the competing solvent processes. However, the management of the Canadian plant that currently produces all of the Swiss Water Decaffeinated coffees sold in North America continues to make determined efforts to refine and improve the process.