The anion and cation resins in the mixed bed are in a mixed state. Each pair of anion and cation can be regarded as a first-level multiple bed. The mixed bed contains many such multiple beds. In the mixed bed, anion and cation resins In contact with each other, the reaction of anions and cations proceed almost at the same time.
As a result of the reaction, the anions and cations in the water are adsorbed by the anion and cation resins, reducing the salt in the water. This is the principle of desalination in a mixed bed.