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Water for Injection (WFI) is the purest grade of bulk water used in the pharmaceutical industry.
With extremely low levels of bacteria, endotoxins and other contaminants, it’s an essential ingredient in products that are introduced directly into the bloodstream.

What’s the difference between Hot and Cold WFI?

WFI can be produced via distillation (Hot WFI) or a membrane system (Cold WFI). Until recently, the only permitted method within Europe was distillation. However, changes to the European Pharmacopeia in 2017 have now given pharmaceutical manufacturers the choice of producing WFI via either process:

1. Distillation (Hot WFI)

This traditional hot process involves a phase change of water into steam to remove bacteria and endotoxins, before condensing the steam back into liquid. High operating temperatures ensure optimal water purification with low contamination risks. On the other hand, there are significant downsides like high energy costs and large system footprints.

2. Membrane systems (Cold WFI)

Cold WFI production methods include reverse osmosis combined with a secondary membrane such as ultrafiltration. Compared to distillers, membrane systems often have lower costs and take up less space. The drawbacks are greater contamination risks and monitoring needs due to ambient (“cold”) operating temperatures, but these can be mitigated with periodic hot water sanitisation.

Which WFI option is right for your pharmaceutical business?

The trade-off between cost and risk can make it difficult to decide whether Hot or Cold WFI is best for your business. So we’ve put together some free resources to help you find out more about your choices:

Discover Cold WFI with our on-demand introductory webinar

If you’re new to Cold WFI, this 45-minute webinar is a great place to start. Presented by Veolia experts alongside Mettler Toledo representatives, you’ll learn the benefits and challenges of Cold WFI and how the risks can be overcome.

Click here to watch >>

Learn more about your WFI options in our blog post

Take a look at our blog post to find out the different factors you need to consider when choosing between Hot and Cold WFI, as well as our range of distillation and membrane systems designed to meet all your WFI requirements.

Learn more>>

Explore WFI in more depth with our white paper

- a comprehensive overview of all aspects of WFI. You’ll learn more about the recent regulatory changes, WFI water standards, pros and cons of Hot vs. Cold processes, and how to choose the right WFI system for your business.


With over 100 years within the industry, Veolia Water Technologies UK are an established provider of water treatment solutions and services.

Speak to a Veolia Water Technologies expert today.

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