Distilled water vs deionised water explained with key differences, applications, purification methods, and FAQs for lab and industrial use.
Distilled water is purified by boiling water into vapour and condensing it back into liquid to remove impurities, while deionised (DI) water is purified using ion exchange resins to remove charged particles such as calcium, magnesium, and chloride.
Although both are widely used in laboratories, pharmaceuticals, industries, and households, they are not the same. Understanding the difference is essential for selecting the right type of water for your application.
This article explains:
Distilled water is produced through distillation, a purification process where water is:
This process removes dissolved salts, minerals, microorganisms, and most organic impurities.
Related: Pharmaceutical Analysis
Deionised water is produced using an ion exchange process, where positively and negatively charged ions are removed.
| Feature | Distilled Water | Deionised Water |
|---|---|---|
| Purification Method | Boiling and condensation | Ion exchange resins |
| Removes Ions | Yes | Yes |
| Removes Organics | Yes (most) | No |
| Removes Microorganisms | Yes | No |
| Energy Requirement | High | Low |
| Cost | Higher | Lower |
| Ionic Purity | High | Very high |
| Storage Sensitivity | Low | High (leaches ions easily) |
While both distilled and deionised water are purified forms of water, they serve different purposes. Distilled water provides broad-spectrum purification, while deionised water offers exceptional ionic purity. Selecting the right type depends on process sensitivity, purity requirements, and cost considerations.
Related:
Technically, yes, but not recommended. DI water lacks essential minerals and can draw minerals from the body if consumed in large amounts.
Both are highly pure but in different ways. Distilled water removes microbes and organics, while DI water excels in ionic purity.
For general lab and cleaning purposes, yes. For ion-sensitive applications, DI water is preferred.
Not long. DI water rapidly absorbs CO₂ and ions from air and containers. Use fresh or store in closed systems.
Distilled water can be made using a home distiller. DI water requires ion exchange resins and is impractical for home use.
No. Distilled water uses heat-based purification, while DI water uses ion exchange to remove charged particles.
No. Additional filtration or UV treatment is required.
Very poorly, due to the absence of ions.
Because it lacks ions, it can leach minerals from containers and metal surfaces.
Both are used, but DI water is often a step in producing Purified Water and WFI.
No. Reverse osmosis removes many impurities but does not fully remove ions like DI systems.
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