The amount of water produced by the purification systems of the laboratories is sometimes insufficient for the demand they must supply, so the storage of pure water (type II) is used for the production of ultrapure water (type I).

However, pure water can absorb impurities during storage, a situation that increases over time due to the existence of multiple sources of contamination in the laboratory. This contamination, which can be in the form of ions, gases, bacteria, endotoxins, silica, can seep through the walls of the water tanks and reach the stored water. Contamination can even come from the container itself.

In the pharmaceutical sector, efforts are made to reduce the degradation of pure water, using techniques such as recirculation through ultraviolet lamps and sterilizing filters, among others. However, these methods offer varied effectiveness, are costly and are not compatible with laboratory water purification systems designed to produce in the range of 10 to 200 liters per day.

Characteristics of containers for the storage of pure water

Appropriate and very clean containers should be used in order to avoid further contamination of the water. The use of high density polyethylene (HDPE) is recommended for the storage of pure water prior to further purification.

Containers should be opaque, with a smooth inner wall that hinders bacterial growth; the container material should be resistant to leaching and corrosion, allowing the maintenance of pure water quality during storage, in terms of resistivity, TOC value and bacterial content.

Ultrapure water storage considerations

Storage of ultrapure water is generally not recommended because it is highly reactive when exposed to air. Its quality is rapidly reduced when it binds withCO2 to form carbonic acid, carbonate or bicarbonate, which promote a change in the pH value of the water .

Also, high purity water has a high affinity for chemicals in the environment; it can easily absorb chemicals from storage containers and pipes, as well as chemical vapors from laboratory air.

Polyethylene containers, wash bottles and glass bottles that are regularly used for water storage in laboratories can leach organic molecules into the stored ultrapure water. This makes the water unusable for sensitive analyses. For example, some studies have shown that the quality of an analysis such as high-performance liquid chromatography decreases when using ultrapure water that has been stored for some time in a polyethylene container.

Therefore, it is recommended to use ultrapure water immediately after production. One of the benefits of having a purification system in the laboratory is the ability to produce ultrapure water on demand. However, if you have no other option, always make sure that your apparatus and storage vessels are appropriate.

Alternative for ultrapure water storage

Storage of ultrapure water is a challenge for laboratories because water quality has been shown to degrade with storage time. This degradation occurs due to contamination of the water, which can come from a variety of sources, including the container and air entering the storage container.

Recently, significant progress has been made in the study of materials for water storage containers and their design. Studies have shown that, with the use of polyethylene and a suitable processing technique, very good quality containers can be obtained for the storage of purified water.

Ultraviolet radiation and a ventilation filter have also been incorporated into these storage systems, which has eliminated bacterial proliferation on the container walls and prevented the entry of contaminated air into the container.

These studies have concluded that, with the use of appropriate materials, proper design, as well as the incorporation of an optimized aeration filter and a bactericidal ultraviolet lamp, it is possible to maintain high purity water quality during storage.

Kalstein water purification system

At Kalstein we have for sale a wide variety of water purification systems of the YR series. You will find different models that adapt to the different needs of each laboratory or clinical diagnostics. Kalstein systems offer high precision resistivity monitoring, ion concentration measurement and TOC monitoring to prevent organic contamination. In addition, they are easy to operate, with a user-friendly graphical interface. They also allow quick cartridge replacement and the supply of pure and ultrapure water is convenient. For more information about Kalstein water purification systems, please visit the link HERE. We are a manufacturer, so you can purchase Kalstein water purification systems at advantageous prices. For more detailed information, please visit HERE