Mixed Bed Deionization Systems are used to fine down the reverse osmosis outlet water by removing the low amounted residual conductivity. Strong anionic and strong cationic resins are used mixed, together and applied to the water in a sequenced way among the resin bed. As such, demineralized water can reach <0,2 µS/cm conductivity value. When the resin column reachs saturation, resins are decomposed by backwash and regeneration. Regeneration is done for the anionic and cationic resin bed seperately. For an efficient decomposing and backwash, resin type must be chosen “Mixed Bed Grade”.