Mixed bed is typically cation and anion ion exchange resin all in one mixture.

Mixed bed ion exchange resin are mainly used in the water purification industry for polishing process water to achieve demineralized water quality, usually after a reverse osmosis system.

The mixed bed ion exchange resin for water treatment are the typical resins with mixture of strong acid cation resins in H+ form and strong base anion resins in OH- form. The ratio of component resins is designed to provide high capacity depending on the application.Several mixed bed resins are available with indicator which facilitate the operation because of color change when exhaustion.