Fistreem International specialises in manufacturing water purification products, with Cyclon and Calypso water stills being well-known globally.

Our new Hydros deioniser is a reliable and cost-effective option for laboratories needing pure water.

Why is it important to use pure water in a laboratory?

Pure water plays a vital role in practically every life science experiment to produce reliable and repeatable experiments. The quality of water used in your experiments is as important as the quality of all other reagents you use to prevent contamination and ensure the best results.

Laboratory water quality also affects analytical instruments’ performance and operating efficiency. The use of good quality water not only ensures improved results but also helps to maintain equipment and reduce maintenance and downtime over its life.

What is deionised water?

Deionised water (DI) is water that has had all (or the majority) of its ions removed. The process of deionisation removes inorganic ions such as calcium or sodium, often picked up through the soil, and copper picked up from the water pipes. A diagram showing the full process can be found below.

How do you produce deionised water? 

Deionisation systems work by replacing negative and positive molecules in water with hydrogen (positive) and hydroxyl (negative) molecules. This is achieved by chemically using synthetic ion-exchange resins to remove ions from feedwater. As the water passes through, hydrogen and hydroxide ions exchange for dissolved minerals and then recombine to form water. 

Deionisation resin beds or columns are typically made from cation-exchange and anion-exchange resins in separate beds or packaged together. 

There are three types of deionisation: co-current, counter-current and mixed bed.

Co-current deionisation refers to the original downflow process where input water and regeneration chemicals enter at the top of an ion exchange column and exit at the bottom. 

Counter-current deionisation comes in two forms. The first form is up flow columns where input water enters from the bottom and regenerates from the top of the exchange column. The second form is upflow regeneration, where water enters from the top and restores from the bottom. 

Mixed bed deionisation is a 50/50 mixture of carbon and anion resin combined in a single ion exchange column. 

It is important to note that resins must be replaced or regenerated according to the manufacturer’s recommendations when the conductivity of the outlet water exceeds 15µs. Therefore, the resin must be checked regularly to ensure that they are not saturated and produce sufficient purity. The Fistreem Hydros deioniser has a built-in conductivity meter that is easy to read, and you can quickly determine the efficiency of your cartridge.

How is deionised water different to distilled water?

Deionised water and Distilled water are both types of pure water, but they are produced in two distinctly different ways. Distilled water is produced by condensing steam from boiled water and then collecting that condensation. In contrast, deionised water goes through a process of filtering, including a resin, to deionise ions from other contaminants.

What is deionised water used for?

Deionised water can be used for a range of different industries for multiple applications, including general lab work, clinical biochemistry, electrochemistry, cell and tissue culture, molecular biology, mass spectrometry and spectrophotometry. Unless very high-purity water is required, deionised water can be a suitable alternative as it can be produced quickly and more economically.

Looking for a Deionised water purification system?

At Fistreem International, we offer a range of world-leading water purification products, and the latest addition to the Fistreem family is the Hydros deioniser, which utilises deionisation to eliminate water impurities, providing you with readily available clean water. Its compact benchtop design and easy set-up make it a valuable addition to your laboratory.

Want to know more? Check out the website at or contact us directly at

About the Author

Hi, I am Lindsey, the Product Specialist for Syngene, Fistreem and Gallenkamp brands. I have worked at Synoptics for 14 years, working closely with the Support, R&D and Sales teams. I am experienced in molecular biology with a Doctorate in Philosophy focusing on molecular neuropsychopharmacology.


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