Why Use Deionized Water?

Deionized water is a common component of a chemistry laboratory and in the manufacturing industry. Understanding how and why this water type is preferable to simple tap water can help you to understand its importance in providing you with the best manufacturing and chemical results.

Glass of water (Image: Design Pics/Design Pics/Getty Images)


Water that comes from your faucet contains ions that are naturally found in the soil, according to the Illinois Department of Physics. Examples of these ions include sodium, calcium, iron and copper. In deionized water a specialized process is used to remove these ions.


An estimated 4 to 6 gallons of tap water are required in order to produce just 1 gallon of deionized water, according to the IN USA Corporation, a chemical instrumentation company. Deionized water utilizes specialized resins to perform exchanges — such as one resin molecule for every sodium, iron or other ion. Once the exchange is complete, no further ions remain and water is deionized and ready for use.

Uses in Chemistry

Using deonized water in the chemistry laboratory is important because the ions found in water can affect your experiments. Incorporation of these ions, even if in only small amounts, can cause your experiments to receive false results — or to not work at all.

Additional Uses

Deionized water is the water of choice in many factory and manufacturing settings, because manufacturers want to avoid the buildup of salts on machinery. Deionized water may be used to cool, lubricate machines as well as other applications in an industrial setting. Deionized water can be used to manufacture cosmetics, medicines and also process foods.


While you can drink deionized water, not all deionized water is suitable for public consumption, according to the Illinois Department of Physcics. This is because deionized water in the chemistry laboratory contains specialized resins used to remove the ions. These resins may have harmful effects on the body. However, if the water is labeled for public consumption, it is safe to drink.

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