Deionized water, also known as demineralized water (DI water, DIW or de-ionized water), is water that has had its mineral ions removed, such as cations from sodium, calcium, iron, copper and anions such as chloride and bromide. Deionization is a physical process which uses specially-manufactured ion exchange resins which bind to and filter out the mineral salts from water. Because the majority of water impurities are dissolved salts, deionization produces a high purity water that is generally similar to distilled water, and this process is quick and without scale buildup.Deionized Water Service, often referred to as “Portable Exchange Deionization” (PEDI), uses tanks containing deionization resin plumbed into your water lines with quick-connect connectors and exchanged as-needed by fresh tanks. This way you have minimal up-front investment by eliminating complicated plumbing and installation and you’re only paying for the high-purity water that you need.