Technologies in Water Purification
What is Water Purification?
Water purification is a process where water impurities, such as contaminants, inorganic compounds or bacteria are removed from the water, leaving it in a purer state. Most of the time, the source water for most laboratory and clinical applications is tap water. With water purification technologies this is processed to the required water type.
Why is Purifying Water Important?
It is important that impurities are removed and additional contamination is managed effectively. If source water is used in applications with no modifications to its condition, then the impurities are capable of influencing the data obtained in these applications. This can render the results invalid and unusable.
What does Water Purification Allow you to Remove?
In its natural state, there are many substances that can be found in water. These include:
• Bacteria and Micro-organisms
• Organic and Inorganic compounds
• Particulates
• Dissolved Gases
For more information on each contaminant type, check out our impurities page.
How do you identify the condition of your source water?
You will never be able to tell the purity levels of water through visual inspection alone, a deeper inspection using microbiological analysis is a necessity. Following this you know the condition of your source water and how to proceed.
What are the methods of water purification used?
There are many different technologies you can use to create pure water from potable water supplies, often in combination with each other. The technology best suited for your needs depends on the application you require it for, as well as the grade of water needed, whether it’s ultrapure water (type i) through to type iii. Costs are another factor to take into consideration, the cost of the whole treatment process will also influence the technology you select.
Water purification technologies used in medical and chemical applications include:
Water purifier technology: Frequently asked questions
- How does reverse osmosis work?
Reverse osmosis (RO) pushes water through a semi-permeable membrane under pressure. The membrane rejects roughly 95–99% of dissolved salts, along with larger organic molecules, particulates, bacteria and pyrogens, while purified water passes through. RO is typically used as a bulk or primary stage, followed by polishing to achieve ultrapure (Type I) water.
- What is the difference between reverse osmosis and deionization (RO vs. deionization)?
RO uses a membrane to remove a broad range of impurities — ions, organics, microbes and particulates — to a moderate level. Deionization (ion exchange) uses resins to target dissolved ions specifically and can reach Type I resistivity (up to 18.2 MΩ·cm). They are complementary: RO does the bulk removal, and deionization polishes the water to ultrapure. RO does not remove all ions on its own, and deionization does not remove non-ionized organics, particles or bacteria.
- How does electrodeionization (EDI) work?
EDI combines ion-exchange resins, ion-selective membranes and a direct electric current to remove dissolved ions continuously. The electric current also regenerates the resin electrochemically, so EDI runs without the chemical regeneration required by conventional deionization. It is usually placed after RO to deliver consistent Type II water.
- Which water purifier technology should I use?
It depends on the water type you need (Type I, II or III), your feed water quality, your application and cost. In practice, technologies are combined — for example RO followed by EDI and/or ion exchange, with UV and final filtration — to reach the required purity reliably and cost-effectively. View our Laboratory Planning page for more information to help you find the best technology for you.
- What is ultrapure (Type I) water?
Ultrapure (Type I) water is the highest laboratory grade, with resistivity up to 18.2 MΩ·cm at 25°C and very low levels of ions, organics (TOC), particulates and bacteria. It is produced by combining technologies — typically RO or EDI for primary purification followed by ion exchange, UV and ultrafiltration polishing.
How each technology maps to the PURELAB purification stages
| Purification stage | Technologies used | Purpose | Suggested PURELAB product link(s)* |
|---|---|---|---|
| Pre-treatment | Activated carbon, reverse osmosis (± softening) | Bulk removal of chlorine, organics, particulates and the majority of dissolved ions to protect downstream stages. | |
| Primary purification | Reverse osmosis / EDI | Produces Type II/III water and feeds the system reservoir. | |
| Polishing | Ion exchange (DI) + UV (185/254 nm) + PureSure® | Removes residual ions and organics to deliver ultrapure Type I water, with PureSure® monitoring for consistency. | |
| Point-of-dispense | Sub-micron / ultrafiltration | Final removal of particles, bacteria and pyrogens at the point of use. |