You're thinking of the method called '(Swiss) water decaffeination', which does indeed only use water. However, these also exist other methods, some of which d

You're thinking of the method called '(Swiss) water decaffeination', which does indeed only use water. However, these also exist other methods, some of which do use solvents: https://www.compoundchem.com/2018/09/26/coffee-decaffeination/ https://www.compoundchem.com/2018/09/26/coffee-decaffeinatio...