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Deionized Water

Diesel Exhaust Fluid (DEF) is defined as a mixture of 32.5% urea and 67.5% deionized water. You can discover more about what urea is here, but deionized water is often the ignored portion of the urea solution. Deionized water is extremely important to maintaining the quality of DEF, which is why it deserves to be discussed as well! Deionized water is used in several industries, and the level of purity is always important. Read on to discover what deionized water is, why it’s used, and how it’s used in DEF!

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Deionized water has a name that defines exactly what it is. Deionized water is just water that has had the ions removed. Remember that your tap water has many ions derived from the ground, pipes, and other similar sources. Deionized water is nothing like your tap water. Think of it as similar to ultra-purified water!  Humans shouldn’t drink deionized water since important minerals attained from drinking regular water are removed. Continued consumption of highly purified water would leave the body devoid of many needed minerals like calcium, magnesium, and sodium. In fact, the consumption of “hard” water or water with minerals is encouraged due to its association with beneficial cardiovascular effects.

Why de-ionize water?

There are many reasons why industries will de-ionize water. The ions in water can cause interference with several different substances. Chemists often use deionized water to conduct experiments to determine what was contained in soil or smoke. If they used regular water, the contaminants could interfere with the experiment result in the wrong conclusions. Additionally, deionized water does not conduct electricity as much as water with ions in it does. Deionized water is also used to dilute concentrated anti-freeze, as a detergent, in the perfume industry, in creating circuit boards and other technological equipment, in automotive cooling systems, and even in freshwater and marine aquariums! There are plenty of industries that currently and will continue to use deionized water.

Water Grades

Since deionized water is used in so many industries, it must be regulated. Under the International Organization for Standardization (ISO), purified water has been classified into three grades. Water that is Grade 3 is the least purified of the deionized water while Grade 1 is the most purified. The highest grade required for DEF is Grade 3, but Victory Blue uses Grade 1 water to ensure the maximum amount of purity is maintained.


A solution of solid urea is dissolved in deionized water in order to produce a concentration that is 32.% urea and 67.5% deionized water. So why does the urea have to be dissolved in purified water? The answer to that lies in the Selective Catalytic Reduction (SCR) system. The SCR system is extremely sensitive to chemical impurities and minerals, which could lead to damages and then losses. Using tap water for DEF could create corrosion or even a total system malfunction. Therefore, DEF must be created using the purest water available!

If you have any further questions about deionized water or DEF, please don’t hesitate to contact us!