Distilled Water Vs. Deionized Water

The water in which dissolved minerals, salts, organic matter, ammonia, CO2, and other impurities are removed is called distilled water. It is produced by the distillation process and is pure and more expensive than deionized water. 

The water in which all the dissolved ions and minerals are removed is called deionized water. Deionized water (DI) is also called demineralized water (DM). It is produced by the deionization process and is cost-effective to use in general laboratories when high-grade pure water is not required. Some of the differences between them are given below:

Distilled water vs deionized water


Distilled and deionized water are pure forms of water. Distilled water is purer than deionized water because organic matter and bacteria are also removed, along with minerals and ions. However, there is a chance of the presence of volatile organic impurities.

Deionized water only removes the charged nonorganic particles (ions). The additional filtering system called reverse osmosis further aids in eliminating the contaminants. 


Distilled water is more expensive than deionized water because the production of distilled water is time-consuming and needs fuels, electricity to boil the water, and a sterile container for its storage. 


Distilled water is produced by the distillation process in which the water is boiled, evaporated, and then re-condensed. This separation process extracts pure water vapor from its impurities. Since water has a lower boiling point than most minerals and impurities, water evaporates, whereas such minerals are left behind. Some of the water is double or triple-distilled, too, to get high-grade purified water. The condensed water is collected, and it is boiled and condensed again and again. 

The deionization process produces deionized water. Water is passed from the bed of ion-exchange resin. The charged ions Ca2+, Mg2+, HCO3, and NO3 are replaced with hydrogen (H+) and hydroxide (OH) ions which combine and form H2O. There is no charge in the deionized water, which makes it a poor conductor of electricity. 


Distilled and deionized water is used in laboratories as a solvent to prepare solutions. It is used in autoclaves and in cleaning glassware. Purified water is used in batteries, cooling systems, aircraft engines, and gas turbine engines. Deionized water is cheaper than distilled water, so it’s preferred in the laboratory. But for medical, which requires highly purified water, distilled water is used in that case.

Can we use distilled water and deionized water for drinking? 

Drinking water, like tap water, is rich in minerals and ions, which confer health benefits.  For example, calcium helps strengthen the bones, and magnesium and potassium promote blood circulation. Both distilled and deionized water is pure water but not suitable for drinking because it lacks the essential minerals required for the body. Its prolonged use may harm us. 

Can we use tap water instead of distilled and deionized water? 

If tap water is used in the laboratory, the ions and organic compounds may cross-react and produce false results. Tap water has a high calcium content, so it can accumulate and corrode the metal parts. So, pure water, like distilled and deionized water, is used in the laboratory instead of tap water. 

Which one is better to use, distilled water or deionized water? 

Among the distilled and deionized water, deionized water is more corrosive than distilled water because it can absorb more carbon dioxide from the atmosphere. When the CO2 is dissolved, it forms a weakly acidic solution of carbonic acid. This affects deionized water’s pH and causes metal parts corrosion, particularly steel. So when there is long-term contact of the metal with the water, distilled water is preferred.

Distilled water is used in pharmaceuticals in preparing analytical reagents and pharmaceutical ingredients. In medicine, distilled water is used to clean wounds, irrigation solutions during surgery, mouth rinsing during dentistry, and in constant positive airway pressure machines. 

Deionized water is not used in medical applications because organic contaminants are not removed from it and contain bacteria and viruses. In such cases, the infection may occur from the deionized water and cause serious health issues. Distilled water is suitable for the long life of the battery. 


  1. Bell-Young, L. (2020, September 8). Can I Use Deionised Water Instead of Distilled Water? ReAgent Chemicals. https://www.chemicals.co.uk/blog/deionised-water-or-distilled-water 
  2. Distilled Water, Laboratory Reagent Grade, 4 Liters.https://www.rpicorp.com/products/biochemicals/water/distilled-water-4-l.html
  3. Deionized Water Vs. Distilled Water – Knowing The Difference.https://www.uswatersystems.com/deionized-water-vs-distilled-water
  4. Deionized Water vs Distilled Water: What’s The Difference? Culligan Los Angeles.https://culliganla.com/blog/2020/12/02/deionized-water-versus-distilled-drinking-water/ 

Sushmita Baniya

Hello, I am Sushmita Baniya from Nepal. I am a postgraduate student of M.Sc Medical Microbiology. I am interested in Genetics and Molecular Biology.

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