Demineralised Water Uses

by ReAgent Chemicals

Demineralised water is a form of purified water that has had all of its minerals removed through a process of ion exchange. This makes it ideally suited to a large range of uses, from pharmaceutical manufacturing to the automotive industry.

Why is Water Demineralised?

The process of demineralisation via ion exchange is a process that is employed to remove any impurity ions and mineral salts from raw water. This process can be used to produce deionised water and demineralised water.

Water is demineralised because the impurities found in raw water, including magnesium, calcium and sodium, would compromise the validity of various industrial processes by interfering with and contaminating other substances.

For many scientific and industrial processes, it is crucial that purified water is used in order to avoid these compromises. It is also important for water to be demineralised so that it can be safely used on sensitive equipment or surfaces without causing corrosion. This is especially important for the automotive and electronics industries, as well as the cleaning of glassware in the lab.

Someone cleaning a petri dish in a lab

The Uses of Demineralised Water

The lack of impurity minerals in demineralised water suits it towards a wide range of industrial applications. This is because it is unlikely to corrode or contaminate other substances or materials.

  1. Laboratory Applications

Water is more than just a vital liquid for the body. It is also a very common and important substance in every lab. It is used as a solvent, to prepare buffer solutions, to dilute chemical concentrations and as a cleaning agent for equipment and containers.

However, common drinking water can’t be used to carry out these processes. Purified water is especially important in laboratory applications because it:

  • Ensures that data obtained is precise
  • Maintains the integrity of analyses, experiments and final products
  • Won’t leave behind unwanted residue on sensitive equipment or in formulations

Certain impurities in water can easily render many laboratory applications useless. For these reasons, demineralised water is used as a way to ensure that chemical processes are kept precise, conditions are kept sterile and results are kept reliable. Its uses in this sector include:

  • As a solvent to prepare things like solutions and buffers
  • In autoclaves to extend the life of the chamber and steam generator
  • Cleaning glassware and other sensitive equipment to ensure no contaminating residue is left behind

While demineralised water is free of mineral salts and most ionic impurities, it is not entirely pure. This is because the deionisation process it goes through does not remove organic impurities, like bacteria, since these do not have a charge. These kinds of impurities could also interfere with laboratory processes and so in some cases, where the specifications are very strict, distilled water is used instead of demineralised water.

The ReAgent Ltd lab

  1. Automotive Industry

The calcium content in water is often problematic in the automotive industry because it can cause a level of build-up that will eventually corrode the metal parts. Since demineralised water has had all of its minerals removed, including calcium, it is often used in the automotive industry as a way of preventing this corrosion from happening. Demineralised water is most commonly used in:

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

Many types of purified water are used in the automotive industry, including deionised water and distilled water, and these can be used in everything from aircrafts to the high-speed SuperSonic car.

But each form of purified water has varying degrees of effectiveness, and demineralised water can have some negative effects when in contact with certain metals. This is because, depending on the purity level of the water, it can actually cause corrosion. Demineralised water has an especially rocky relationship with carbon steel as it can degrade the metal via oxidation and acid corrosion.

This isn’t because demineralised water is corrosive but rather because it can contain dissolved gases, like oxygen and carbon dioxide, which make it corrosive by reacting with the metal.

  1. Pharmaceutical Manufacturing

Pharmaceutical grade water is widely used as a raw material, ingredient and solvent in the formulation and manufacture of a variety of pharmaceutical products, including:

  • Compendial articles
  • Analytical reagents
  • Active pharmaceutical ingredients (APIs)
  • Active pharmaceutical intermediates (APIs)

When used in pharmaceutical and cosmetic products, demineralised water is referred to as ‘aqua’ and it helps to control the quality and safety of the contained ingredients.

Green and black medicine capsules spilling out of a container

  1. Electronics

In the electronics industry, washing circuit boards is a common and important process. This is because, after a board has been manufactured, a substance called flux is left behind. It is important to remove this from the board as it can create corrosion and impact longevity.

The type of water used in the washing of circuit boards is usually demineralised or deionised water since these are very similar. Demineralised water is used here for a similar reason as to why it is used in the automotive industry.

Since normal tap water contains impurity ions, it should not be used to wash circuit boards as it will leave a salt residue behind as it evaporates. Eventually, these salts will react with normal air and cause corrosion to the surface. The residue also has the potential to create shorts in the circuit boards.

Therefore, circuit boards are rinsed with demineralised or deionised water in order to side-step the long-term reliability problems that would occur if salt residues were allowed to accumulate.

  1. Other Uses of Demineralised Water

Demineralised water is an incredibly versatile product that is essential in many industries beyond automotive, pharmaceutical, electronics and the lab:

  • It is used in the petrochemical sector to treat cooling tower blow-down
  • It is used in high-pressure boiler feeds in power industries and refineries
  • It is used in steam applications like steam irons and steam raising
  • It is used in commercial window cleaning for sparkling results
  • It is used in aquariums to control the water pH levels
  • It is used in laser cutting and laser cooling
  • It is used in water mist fire extinguishers

Its diverse range of applications demonstrates how important demineralised water is not only for industrial processes but scientific processes, too. However, it is important to note that demineralised water is not for human consumption precisely because of its lack of minerals.

While this may sound desirable, the minerals in normal tap water are crucial to our diet, and the consumption of demineralised water not only prevents us from getting these essential minerals, it can also remove existing minerals as well as electrolytes from the body.

Close up of a circuit board, which demineralised water is used to clean

ReAgent supplies high-quality demineralised water in a range of pack sizes and grades. We are internationally recognised for our industry-leading customer service, and every one of our products is backed by a 100% quality guarantee. Place your order online today or call our customer service team with any queries you may have.


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