Scale, Taste and Odor Removal. The process used for removal of all dissolved salts from water is referred to as deionization or demineralization. Deionization requires the flow of water through two ion exchange materials to affect the removal of all salt content. The use of an indicator dye, bound to the resin, that changes colour is specifically intended for use in clear housing. Such systems are designed without meters and rely on the changing colour of the mixed bed resins to indicate exhaustions and replacements of filters.