Knowing How Deionized Water is Achieved

Published: 07th July 2010
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Deionized water has become very important these days that its production is highly anticipated in many industries. It is also called DI water or demineralized water and is often compared to distilled water, which is essentially similar to it. Manufacturers of medicines, chemicals, food, cosmetics, and car batteries use this type of water. Also, many rinsing and cleaning chemicals contain water that has undergone deionization.

Deionization of Water

Water never comes pure in nature and this is why companies need to purify it to a usable extent. There are various treatment methods to ensure its pureness and potability. Water coming from the natural sources contains many impurities (minerals, organic compounds, microorganisms, and microscopic organic matter). These impurities should be removed and their concentration must be reduced to a negligible or harmless extent. For this to be possible, raw water must undergo several treatment steps.

Water usually undergoes filtration and is passed through layers of sand to remove sediments. Activated carbon then filters out colloidal particles. The resulting water may still be unsafe due to bacteria and substances whose molecules are small enough to pass through porous filters. There are many ways to remove smaller molecules and bacteria. Reverse osmosis is the next process employed to remove organic molecules. It may remove bacteria and microorganisms but other water companies employ ultraviolet treatment.

The resulting water may be potable but still has considerable ion content. Ions result from the dissolution of mineral salts in water. These salts occur in the natural environment and because ions are very small they are able to pass through filters and some remain even after RO process. There are two basic ways to remove these ions namely, distillation and deionization. Deionization is employed by passing water through ion exchange resin beds.

There are home water softeners with resins containing sodium ion (Na+), which replaces calcium (Ca++) and magnesium (Mg++) ions. But for overall removal of ions in water, negative and positive ions should be removed. In more sophisticated deionization systems, water passes through a resin bed that contains hydrogen ions (H+). The hydrogen ions replace all the positive ions in the water. The resulting water would still contain negative ions which are replaced by hydroxyl ions (OH-) in the second resin bed. The water that comes out is extremely pure water that is devoid of ions or minerals.

Relevance of DI Water

Water for general home use need not undergo deionization. Sanitary drinking water may contain some ions but deionization is not a hygienic requirement. However, many people prefer deionized or distilled water not because of the absence of ions but because the process it undergoes ensures its safety. DI water undergoes such a stringent treatment process that it becomes ultra pure and very safe for drinking.

The production of water devoid of ions, however, is quite relevant in many industries. As mentioned in the first paragraph, demineralized water is important part in the production of food, medicines, and cosmetic products. In laboratories, pure water is needed to rinse laboratory glassware. Autoclave water used to disinfect medical instruments is also essentially DI water.

This kind of water is used in specialized applications wherein tap water is inappropriate. Plain mineral water contains considerable concentration of ions that affects the quality of resulting products in industries. Deionized or demineralized water is also important in industrial cleaning because water with enough mineral content can cause scales in equipment that either lower the efficiency or ruin the equipment after a time. If you heard that car wash companies use DI water as the final rinse, that's because you want to see your car surface and windows spotless after the cleanup. Without ions in the water, it cleans efficiently without leaving any scales or spots.

Jo is a content writer for 'Deionized Water' (, a site owned by, an established UK based high quality water supplier for over 30 years, supplying products such as demineralized water and deionized water to a an extensive variety of consumers in UK, Europe and all over the world. If your corporation has a deionized water supply needs then have a look at

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