Deionized water refers to water that is free from all ions and has virtually no charge. This state is usually achieved by running our water supply through an electrically charged resin. The resulting deionized water is highly reactive. This property means that any exposure to air will cause a reaction that changes its properties.

So how do we make deionized water? What are its advantages, and is it better than our regular distilled water?

We have answered all these questions in this article! Scroll on to learn further.

Table of Contents

Why is Deionized Water Necessary?

Deionized water is completely blank water. It is ready to react with any component and is essentially pure water. Deionized water has a pH value of 7 and is completely neutral. This property is invaluable, particularly to the pharmaceutical companies.

For any medical product, water is a vital component. However, regular water is susceptible to impurities that may cause unwanted reactions. A controlled chemical reaction is necessary to ensure we get the component we need.

For instance, any saline solution that needs to be injected into the body has to meet this standard. The water used in this process is always deionized water. Any presence of impurities such as copper or lead can result in adverse health consequences. You can also study about the positives and negatives of ionized water first and hence decide on whether deionized water is necessary for you or not.

Uses of Deionized Water

Deionized water is beneficial not just to the medical industry but in any industry where pure water is required. Since it is such a good solvent, it can work with ceramics, wood, glass, and so on. The following are some instances where deionized water may come handy:

  • Making chemical mixtures and solutions
  • For laboratory manufacturing of products
  • Diluting anti-freeze chemicals
  • Acid-based batteries
  • Rinsing printed circuit boards
  • Washing any equipment off of alkalis and acids
  • Refilling cooling systems to prevent salt deposits
  • Perfumes and detergents

How to Make Deionized Water?

There can be several ways to obtain water that is free from all ionized particles. The result is pure water that is free from common dissolved impurities such as calcium, chlorides, sodium, and so on. The standard method is to remove these impure ions and replace them with either hydrogen (H+) or hydroxyl ions (OH-). These, when combined, will result in pure water.

Before the deionization process, the water is usually filtered. The filtered water is further put through reverse osmosis. These pre-filtration methods help in removing all the organic wastes as well as sediments from the water. This filtration ensures that we already have relatively clean water going through our ionizer. Doing so ensures maximum efficiency for the deionization process.

Once our water has been appropriately filtered, two ion-exchange resins are used. Each of these resins has a higher preference for other ions. These will then exchange the incoming positively charged ions (cations) and negatively charged ions (anions) for hydrogen and hydroxyl ions.

This way, the resins attract all the impure ions and leave you with deionized water that is ready to be used.

Types of Deionizations

Now that we’ve understood the basic principles of deionization, the next thing to understand is the different types of deionization processes. While the general concept remains the same across this variety, the two most common type of deionizations are listed as follows:

Two-bed Deionization

For the two-bed deionization, we will need two containers. One will contain a cation-exchange resin full of hydrogen (H+). In contrast, the other will contain an anion resin full of hydroxyl (OH-) form.

First, the inflow of water will go through the cation container. Within this tank, all the cations present in the impurities will be exchanged for H+ ions. To maintain a chemical balance, for every monovalent cation, the resin supplements one H+ ion. For every divalent cation, two H+ ions are supplemented. For instance, for every Na+ cation, one H+ ion and for every Ca2+, two H+ ions are replenished.

The water then flows into the second container, where the anion resin functions similarly. For every monovalent anion, the adequate OH- ions are supplemented. The H+ and the OH- ions then combine to result in pure, deionized water that we need.

Mixed-bed Deionization

For the mixed-bed deionization, both cation and anion-exchange resins are mixed in one vessel itself. The water that is deionized from this process tends to be of better quality than the two-bed version. This is primarily because both the cations and anions are thoroughly mixed, which helps this container act as one lengthy deionizer.

However, this efficiency also comes at a price. Mixed-bed deionizers are more prone to contamination. They are also relatively harder to regenerate, so maintenance might be tough. This is why mixed-bed deionizers are typically only used as a secondary purification method. The water is first treated via two-bed deionization or reverse osmosis.

Types of Deionizers

We’ve understood the different deionization processes, the next thing we need to understand is the basic types of deionizers. Though they all function on the same principle, the main difference is the purpose it is used for. Following are the four different types of deionizers:

  1. Disposable Cartridges
  2. Portable Exchange Tanks
  3. Automatic Units
  4. Continuous Units

Deionized Water vs. Distilled Water- Which is Better?

Both deionization, as well as distillation, deliver pure water. But the process is entirely different. There isn’t necessarily one type of water that is better than the other. The difference is simply in the pros and cons and which system is better suited for your purposes.

When water goes through deionization, it targets ions. These are the charged non-organic elements. What this means is that it will not filter your water from any organic impurities. If your water is prone to heavy contamination, then simply deionizing it will not be sufficient to deliver you with pure water.

The distillation process is meant to target impurities- both organic and inorganic. However, no method is 100% effective. As such, there can still be some volatile organic compounds and other contaminants left behind. Distilled water is generally quite pure. But depending upon the application, for instance, laboratories- it might not be pure enough.

Hence, the purification process you opt for should be based solely on the use. For manufacturing, pharmaceutical uses, or industry-grade cleaning, you will most likely need deionized water. Whereas for everyday usage, distilled water should be a right choice.

Benefits of Deionized Water

As we’ve seen from the versatile uses, deionized water can have many benefits. This type of water is the prime choice in any manufacturing setting. Furthermore, it is perfect for batteries or in cooling electronics without risking any unwanted reactions.

Deionized water is also beneficial for the cosmetic industry and during food processing. The use of this kind of water helps ensure that no unwanted elements are added into your manufacturing process.

Another benefit is its usage in cleaning any product for final finishing. Tap water is bound to leave deposits of calcium, magnesium, and so on, but with deionized water, you will have no such problems.

Similarly, drinking deionized water has also been linked with detoxifying your body during short-term usage. Bacteria-free water is always necessary for any biotech-related process. Finally, it is also handy for cleaning surgical instruments to ensure no residuals and high-quality sterility.


The deionization process works by attracting the impure cations and anions and replacing them with H+ and OH- ions. Deionized water is chargeless water that comes with many benefits. However, it is generally not considered to be good for your health. Even if consumed, you should ensure that it is short-term.

Read our newly published article on “Proper Chlorine Level in Pools” here.

(Last Updated on July 14, 2021 by Sadrish Dabadi)

Nina Howell is a Rewenable Energy researcher and consultant based out of Houston, Texas Area. She earned her Master's Degree in Energy and Earth Resources from Austin Jackson School of Geosciences in 2010, and a Bachelor's Degree in Environmental Science from State University of New York College of Environmental Science and Forestry in 2008. Nina has been working in the energy sector since 2011. She worked as an Energy Supply Analyst from 2011 to 2017 in Bounce Energy and then as a Research and Energy Consultant at GE Renewable Energy from March 2017 to February 2020 . Nina is a mom of 2 beautiful children who are joy to her life. She strongly believes in eco-friendly living and is vocal about renewable energy, environmental issues, water crisis, and sustainable living.