Deionised water is water that has been mechanically filtered or processed to remove impurities and make it suitable for use. Deionised Water is purified by a chemical process called Deionization. It uses specially manufactured ion-exchange resins, which exchange hydrogen and hydroxide ions for dissolved minerals, and then recombine to form water.
Deionised water is suitable for many applications, including autoclaves, hand-pieces, laboratory testing, laser cutting, and automotive use. It is commonly used to top up the lead-acid batteries used in cars and trucks and for other applications. Deionised water is the better choice compared to tap water as the foreign ions commonly found in tap water will drastically shorten the appliance lifespan.