Water is used for a lot more than just drinking and washing, and there are entire industries that heavily rely on the water being as pure and uncontaminated as possible. One of the key processes that make the water as pure as it can be is deionization, which removes both the positively (cations) and negatively (anions) charged ions from the water.

These contain minerals and dissolved substances that could potentially interfere with testing and other processes, but why, where, and how of deionization is something that needs to be elaborated on to understand its use.

What is Deionization?

During deionization, both the positive and negatively charged ions are removed from the water. If the water needs to be used on any kind of metal or alloy, these ions can result in corrosion, making deionization necessary for certain processes. Overall, deionization does not remove all the ions, but it does remove a majority of them to the point that deionized water does not contain the same qualities as regular, ionized water.

The process of deionizing water is conducted by water deionization systems that are often part of a larger purification chamber. Hemodialysis, for example, requires as pure water as possible. Deionization alone doesn’t remove the bacteria and other contaminants, but dialysis machines have reverse osmosis and other systems for that as well. The water that comes from a water deionization system has very low conductivity, making it very useful for use with electronic equipment, devices, and similar uses.

Water Deionization Systems – How They Work

While we won’t be getting too much into the technicalities of how water deionization systems work, understanding some parts of it is necessary to understand the benefits and drawbacks of these systems.

Deionization di water systems have resin beds for both cations and anions, which exchange the water from the ions to others with a similar charge. This means that the specific substances are removed almost indiscriminately from the water. So, for example, the minerals we typically get from drinking water would not be present in deionized water. The positive ions, or cations, contain calcium, sodium, magnesium, iron, etc., and the negative ions—anions—contain chloride, nitrate, sulfate, etc. These are replaced with Hydrogen ions (H+) or Hydroxide ions (OH-).

The processes result in the ionic properties being removed via deionization, but that also means some important minerals being removed—making deionized water not necessarily harmful but also not beneficial for drinking purposes. It should also be noted that bacteria are not removed from deionized water, and other processes must be carried out to do so.

The Uses of Deionized Water

Deionized water is excellent for many industries, and they use plenty of it across various industries. Here are a few examples:

  • Cooling Systems

In a cooling solution, water is typically used to transfer heat from one source to another rather than outright remove it by cooling the surface. From radiators to high-powered lasers, water is used in cooling systems everywhere, and the higher efficiency of deionized water means that it is excellent for heat transfer. This can help keep the temperature of the device regulated to ensure a certain temperature level is kept.

  • Laboratories and Testing

Laboratories carrying out tests might need to use water at times. However, the ionic materials in the water are contaminants that can potentially skew the results of the test, for which a deionized, ultra-pure form of water is needed. This is both for testing and cleaning and might even be used to sterilize equipment used in medical procedures.

  • Machinery and Manufacturing

From cleaning huge, heavy machinery used for manufacturing to rinsing tiny semiconductors used in computers, phones, and modern vehicles, deionized water has plenty of use in various industries and manufacturing. Most modern industrial machines are running for extended periods and have to be cleaned regularly to keep their efficiency and prevent breakdowns during routine work. Using regular water might result in corrosion and conductivity building up, rendering the machine otherwise unusable. Deionized water, on the other hand, can avoid the buildup of corrosion and remove dust, grime, and other contaminants. It can even be used to cool and lubricate products.


  • Medical Procedures & Dialysis

Deionized water is used in plenty of medical procedures, but here the main focus will be dialysis and how important this process and its product are in this lifesaving procedure.

Hemodialysis is a procedure where excess fluids and waste are removed from a patient’s bloodstream—a function normally reserved for the kidneys. As dialysis is for patients with kidney failure, it is a necessary and life-saving procedure where ultra-pure water is pumped into the patient’s bloodstream. Impurities in the water can range from causing problems in the procedure to even causing mortality or morbidity in patients. The water used in dialysis undergoes a stringent purification process, and deionization is an important step in this process.

The use of deionized water in dialysis helps minimize the risk of chemical imbalances, electrolyte disturbances, and potential complications that can arise from exposure to impurities. By removing ions and impurities, deionization systems contribute to maintaining the desired electrolyte balance and preventing the accumulation of harmful substances in the patient’s bloodstream. As the injection of water is so direct, very strict standards are set for hemodialysis, and both the water and the dialysis machines have to constantly be tested and maintained.

Moreover, deionized water is essential for preparing dialysate, the solution used in the dialysis machine to facilitate the exchange of waste products and electrolytes during the treatment. The quality of the water directly affects the composition and safety of the dialysate, ensuring proper fluid and electrolyte balance during the dialysis process and making the deionization process even more critical.


When considering the use of water deionization systems, it is important to assess the specific needs and priorities of the application. In some cases, alternative water treatment methods, such as reverse osmosis, may be more suitable, as they can remove a broader range of contaminants while retaining essential minerals.