What Is Demineralized Water?

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Demineralized water is water that has been treated to remove most of its mineral content as a result of distillation, deionization, reverse osmosis, electrodialysis, or another water purification technology. While demineralized water is necessary for many industrial and commercial applications, it is often not consumed as drinking water, because all (or most) impurities are removed, including dissolved minerals, that are beneficial for human health.

Demineralized water is exactly as it sounds, it is water that has been treated to remove all (or most of) various mineral impurities. There are different methods to demineralize water, however, not all water purification methods remove the mineral content in the water. 

So, while water demineralization can refer to any treatment process that removes minerals from water, the term is typically used to describe the ion exchange processes used for the near-total removal of ionic mineral contaminants. This is why demineralization and deionization are often used interchangeably, although they are not necessarily the same. 

In this article, we will discuss exactly what demineralized water is, the difference between demineralized water and distilled water, and what applications use demineralized water. 

How Is Water Demineralized?

Demineralized water has its mineral content removed, and the most common methods to demineralize water are via distillation, reverse osmosis (RO), deionization (DI), and electrodialysis.

In industrial or commercial environments, water is demineralized via distillation and DI, while RO is used in commercial and residential settings, such as households. 

Water is demineralized in the following ways:

  • Distillation
  • Deionization
  • Reverse Osmosis (Membrane Filtration)
  • Electrodialysis

Distillation

Distillation has been around for many years, and it has served as an essential way to remove impurities from water. Water is distilled by boiling until steam is produced, which is then captured, collected, and left to cool. As the steam cools, a liquid is formed again, and during that process, dissolved salts and minerals are removed.

Distillation also removes certain microbial content such as bacteria and protozoa when the water is heated. Water distillation also removes heavy metals and disinfectants that are harmful. 

Distillation does produce highly demineralized water, however, it is not practical for residential applications and uses because the process requires specialized equipment that cannot provide water on demand. 

Deionization 

Deionization is a much more complicated process of demineralized water, and so it is only primarily used in industrial and commercial applications where large amounts of demineralized water are required. 

During the DI of water, water is run through two specialized resins that contain different charges. One of them is positively charged (anion resin), and the other is negatively charged (cation resin). The resins act as exchangers, removing minerals from the water to demineralize it.

Deionization is extremely effective at removing unwanted mineral content from water, yet it is unable to remove many other types of contaminants such as viruses, bacteria, protozoa, and organic chemicals. 

Reverse Osmosis (Membrane Filtration)

If you have ever demineralized water inside your home, then it is likely you have used a RO filtration system. These reverse the natural process of osmosis, providing you with safe, clean, and filtered water. Reverse osmosis is also known as membrane filtration and hyperfiltration, all three terms can be used to describe the demineralization process. 

During RO, water flows over a semi-permeable membrane from a low solute concentration area to an area with a high concentration of solutes. The process continues until both solutions reach equilibrium. The force behind this process is called osmotic pressure.

Reverse osmosis is the leading process of desalination and demineralization. It is used to demineralize and create purified water in agricultural, industrial, manufacturing, and food production applications.

In residential settings, RO systems are used to filter water to produce demineralized water. Reverse osmosis is the most cost-effective way to demineralize water, which is why it is used over distillation processes and buying bottled water. Excessively buying bottled drinking water is also bad for the environment, so many people are finding more environmentally-friendly methods to demineralize water at home, and RO is a perfect answer. Plus, reverse osmosis systems are powerful and small enough to be installed in your home, and out of sight.

Demineralization via RO is also highly effective at removing minerals, salts, and other dissolved solids from water, and if you were to combine an RO system with a carbon post-filter, disinfectants like chlorine and volatile organic compounds can also be removed.

Electrodialysis

Electrodialysis is a type of membrane filtration process used to demineralize water using an electrical field.

The combination of using electrodialysis and ion exchange resins both deionizes and demineralizes the water without the need of regenerating ion exchange resins. 

Drawbacks Of Using Demineralized Water

Demineralized water is technically free from all minerals and contaminants, however, there can often be very minute amounts of dissolved materials still suspended in the water, which will always remain. 

However, with the constant advances in modern-day technologies, demineralization process methods offer some of the best quality water supplies. 

The Difference Between Demineralized Water And Distilled Water

A question often asked is what are the main differences between demineralized water and distilled water? 

Distillation and demineralization are both successful ways to purify water, yet they have different methods to achieve that goal, and they produce different end results. Demineralized water removes minerals from water, leaving you with only water, however, demineralized water can still contain bacteria/viruses.

But, in distilled water, suspended particles, organic materials, bacteria, viruses, and other impurities are removed. Therefore, distillation is a much more effective method of purifying water than demineralization, despite demineralization removing trace elements that slip through the distillation process.  

Because of this, most industries combine demineralization and distillation to produce the purest water. 

Can You Drink Demineralized Water?

It’s not recommended to drink demineralized water, as health experts have reported that drinking extremely pure water can increase the risk of developing multiple mineral deficiencies. 

The best source of drinking water is natural spring water, but not everyone has access to natural sources, nor are they always sanitary enough to drink through a tap. So, the second-best option would be to drink distilled water produced by a water distiller or bottled distilled water. 

If demineralized water is the only source of drinking water, you must make sure you’re getting the minerals your body needs and consider taking hydration supplements such as trace minerals. 

Why Is Demineralized Water Used?

As demineralized water lacks metal impurities, it can support a wide range of industrial applications and uses. This is because demineralized water is extremely unlikely to corrode or contaminate other substances or materials being used. 

Laboratory Applications:

  • Used as a solvent to prepare solutions and buffers
  • Used to dilute chemical concentrations
  • In autoclaves to extend the life expectancy of chambers 
  • As a cleaning agent for equipment and containers, particularly glassware

Automotive Applications:

  • Lead-acid batteries
  • Gas-turbine engines
  • Cooling systems in cars and aircrafts

Pharmaceutical Manufacturing Industries:

  • Used as raw material, ingredient, and solvent in manufacturing and formulating pharmaceutical products 
  • Demineralized water is also used in the formulation of cosmetics to control the quality and safety of the contained ingredients

Electronics:

  • Washing circuit boards

Other Uses Of Demineralized Water:

  • Laser cutting and cooling systems
  • Fire extinguishers
  • Commercial window cleaning products
  • Aquariums to control pH levels 
  • Steam applications (irons, etc.)
  • Cooling towers
  • High-pressure boiler feed systems in power industries and refineries

Summary

Demineralized water is produced using ion-based processes to remove minerals and other water impurities. Because demineralized water lacks impurity metals, it can support a wide range of industrial applications and uses including medical, pharmaceutical, and automotive industries. 

If you have any questions regarding water quality and water purification methods, or you want to know more about the water quality testing kits we have to offer, please do not hesitate to contact our world-class team at Atlas Scientific

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