This isn't really true, there are a few different methods to decaffeinating coffee beans:
"Like regular coffee, decaf coffee begins as green, unroasted beans. The hard beans are warmed and soaked in liquid to dissolve and remove the caffeine in one of four ways: using water alone, using a mixture of water and solvents (most commonly methylene chloride or ethyl acetate) applied either directly or indirectly, or using water and “supercritical carbon dioxide.”"