DEIONIZATION is commonly used in laboratories for producing purified water on demand. Deionization systems have typically consisted of one to four cylindrical cartridges hooked up to plumbing lines and hanging on a wall near a sink.

Deionization functions by exchanging hydrogen ions for cationic contaminants and hydroxyl ions for anionic contaminants in the feedwater. The deionization resins are tiny spherical plastic beads through which the feedwater passes. After a period of time, cations and anions from the water displace all the active hydrogen and hydroxyl groups in the beads and the resin must be replaced or regenerated.

Anions and cations in the feedwater pass through the ion exchanger resins and replace the hydrogen and hydroxyl ions attached. The hydrogen and hydroxyl ions then combine to form pure water molecules.