The Swiss Water Process removes caffeine using only water, temperature and activated carbon filtration — no added solvents.
How it works
A batch of green coffee is soaked in hot water, which dissolves both caffeine and the flavor compounds. That first batch is sacrificed.
The resulting liquid is passed through carbon filters sized to trap caffeine molecules while letting the flavor compounds through. What remains is Green Coffee Extract — water saturated with coffee flavor but with no caffeine.
New batches of green coffee are then soaked in that extract. Since the extract is already saturated with flavor compounds, those cannot diffuse out of the bean — but caffeine can, because the extract contains none.
The extract is recirculated through the carbon filters continuously.
Why it preserves flavor
The clever part is the saturation. The bean has no reason to give up anything except caffeine.
The results
99.9% caffeine free, suitable for certified-organic coffee, and no solvent residue by definition.
The trade-offs
More expensive than solvent methods, so it appears mostly on specialty bags.
Versus sugarcane / EA
The sugarcane process uses ethyl acetate, derived from fermented sugarcane, and is common in Colombian decaf. It often retains sweetness slightly better and it is technically a solvent method, though the solvent is naturally derived.
Both are good. Either beats old-style decaf comprehensively.
Last reviewed 30 October 2026