Choosing the right solution for purified lab water

As purified water is the most common reagents in scientific and laboratory processes it is vital that the correct level of purity is achieved and maintained. While there are different approaches to the supply of pure water it is important to consider the requirements and how it will be used to ensure the best solution is chosen.

Purchasing bottled pure water (also known as packaged water) can seem like the most cost-effective route as it requires no capital investment or ongoing maintenance costs. It may also be seen as a simple option as it can be managed in the same way as other laboratory reagents with clear expiry dates and documentation of its purity.

However, it is important to be aware of the potential issues. Firstly, the stated purity level (Type I, Type II, Type III etc.) only identifies the purity of the water used to fill the containers – the way the water is stored and used as well as the material of the bottle will affect the purity. For example, purified water is commonly supplied in plastic bottles, which if not manufactured and handled correctly may contaminate the water with organic plasticisers, moulding release agents, solvents and monomers – especially if stored for extended periods of time.

Furthermore, once the bottle is opened the purity will begin to degrade. When a quantity of water is removed, air will inevitably be drawn in and bacterial, ionic and organic contaminants will be introduced. Within 5 minutes, what once was ultra pure water is now general grade water due to the absorption of airborne impurities. (see graph below)

Resistivity of pure water in air -  Sourced from Elga

As such the Clinical and Laboratory Standards Institute (CLSI) recommends that labs only purchase volumes of bottled water that can be used quickly to minimise the degree of degradation. This contamination is a particular issue for Ultra Pure Type I water, which due to its very low bacterial and endotoxin levels may become unacceptably contaminated as soon as the container is opened, and caution should be exercised when storing it for use later.

Additional considerations when using packaged water are the possibilities of escalating costs and the level of waste produced. If large quantities of pure water are used by the lab then bottled water can become expensive, especially if it is purchased in relatively smaller quantities to protect the integrity of the water. The plastic waste generated from bottled water can also be significant. It is estimated that across the world labs create around 5.5 million tonnes of plastic waste a year – the equivalent weight of 67 cruise liners.

The alternative to bottled water is investing in an in-house purification system, which can often prove to be more cost effective, especially over the longer term. Even when the whole life cost of the system is considered, including the initial investment and maintenance, very low costs per litre of water can be achieved. These systems also help lower the environmental impact of the organisation by eliminating waste.

There are a range of different systems available to suit almost any size of laboratory or process requirements. A purification system can also provide flexibility in terms of water purity as the needs of the lab change over time.

Contact our team to discuss your requirements and find out more about the systems we offer.

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Peter Bridge

About the Author

Peter Bridge

Peter has a background in analytical chemistry and has gained a wealth of knowledge and experience working for and supplying to a wide range of pharmaceutical, biotech customers and pharmaceutical companies.