There are three main classifications of purified water, so how do you decide which type you need? The answer really depends on how you plan to use it.
Ultrapure ASTM Type I water (the purest grade) is intended for highly sensitive applications such as cell culture and gas chromatography. Type II Purified Water is suitable for general laboratory use, and Type III Primary Grade Water can be used to wash equipment.
Continue reading to learn more about the different types of purified water and their uses.
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Types of purified water
Purified water is mainly classified according to its level of purity. Depending on the standardisation group, it can generally be categorised into the following grades or types:
- Type I (the purest)
- Type II (laboratory grade)
- Type III (for general use)
Water purity is determined by the maximum amount of contaminants you can detect in the water. Contaminants include ions, organic compounds, total solids, colloids, and microorganisms. International standards on the maximum detectable contaminants may vary slightly, depending on the standardisation classification.
Some of the most popular purified water products include distilled water, deionised water, demineralised water, and ultrapure water. You can read more about each of these below.
Distilled water
Distilled water is a type of purified water that’s gone through the distillation process. Although the specific equipment and scale of distillation may vary depending on the intended use, the basic principles are the same.
Distillation involves at least two containers and an interconnecting tube. One container serves as the boiling vessel, while the other is the receiving vessel. To begin with, water is heated beyond its boiling point so that it evaporates and turns into steam, or water vapour. The steam travels through the tube or pipe system and is allowed to cool and condense.
It’s then collected as distillate in the second container, leaving behind the salts, minerals, heavy metals, ions, and other impurities in the original container. Organic matter like bacteria are also removed during this process. However, the purity of distilled water can still be affected by the presence of residual impurities in the tubes and condensing vessel.
Distilled water is used in a range of industrial and laboratory settings, whether it’s for testing, rinsing or cleaning. It’s also commonly used in irons, laser cutting, and in the manufacture of car batteries.
Deionised water
As the name suggests, deionised water contains no ions.
Ions from dissolved minerals and salts in the water are removed through an ion exchange process and replaced with hydrogen and hydroxyl ions. Unlike the distillation process, deionisation can only remove inorganic compounds like minerals and salts.
Deionised water is often used in pharmaceutical and laboratory environments to prepare mixtures and chemicals. It’s also involved in the manufacture of acid and alkaline batteries, household detergents and large-scale heating and cooling systems.
Demineralised water
Demineralised water is another type of purified water that’s made by passing non-pure water through an ion exchange bed. Much like deionisation, this process filters out inorganic mineral salts and other impurities in the water. You can read more about the demineralisation process here.
Demineralised water is commonly used in pharmaceutical settings as a raw ingredient for making various drugs and medicines. Its high purity also makes it a useful testing medium in laboratories.
Ultrapure water
As you can probably guess, ultrapure water is a high grade of water that doesn’t contain any impurities like microbes, minerals, or dissolved gases. Its purity level is therefore 100%, or as close as possible.
Ultrapure water is typically produced through a three-stage process that involves electro-deionisation, reverse osmosis and ultraviolet (UV) light exposure, and finally polishing.
Otherwise known as UPW, ultrapure water is primarily used in the semiconductor and pharmaceutical industries for analytical and manufacturing applications. It’s also used for scientific methods, such as high-performance liquid chromatography and gas chromatography.
Purified water for laboratory use
Laboratories may use different grades of purified water, depending on the type of equipment and application.
For general laboratory use, Type II purified water will often suffice. This is usually sufficient for preparing solutions and reagents. Type II can also be used in many biological experiments such as the preparation of growth media.
However, for clinical and molecular testing that requires more precise results, Type I water is more suitable.
Industrial applications of purified water
Purified water is necessary for a wide range of industrial applications, from food processing to drug manufacturing. For example, in the brewing industry, purified water is used during the fermentation process to minimise the risk of pathogenic microorganism contamination.
Synthesising medicines is also a very precise process; even the presence of a very small number of contaminants can compromise medicine formulations that have been years in the making. This is one of the main reasons why companies use purified water when manufacturing pharmaceutical drugs.
At ReAgent, we supply purified water to a variety of businesses including those in the automotive, food manufacturing, power generation, water treatment, engineering, environmental, and petrochemical industries.
Is purified water the same as distilled water?
Distilled water is a type of purified water that has been through a distillation process.
It’s free from microorganisms and dissolved inorganic and organic contaminants. The degree of purity, however, may vary depending on the process.
Handling & storage of purified water
Purified water is typically stored in plastic containers of varying sizes. These should ideally be kept in a cooler/ refrigerator or, at the very least, not exposed to high heat and direct sunlight.
Purified water is generally safe to handle, although ultrapure water is not suitable for human consumption.
Summary
Generally speaking, there are three main grades of purified water. Choosing the best one for your needs will depend on how you intend to use it. Type I is the purest form and is suitable for very sensitive applications. There are several types of purified water, including distilled water, demineralised water, deionised water and ultrapure water. Some are drinkable but others are mainly used for laboratory or industrial purposes.
If you’re a UK-registered business, you can buy various types of purified water from our online shop. With a range of pack sizes available, you’re sure to find the right product for your needs.
