The Impact of Ultrapure Water Storage on Water Quality

The quality of ultrapure water produced by an ultrapure water system deteriorates over time when stored in the tank. What are the reasons for this deterioration?

1. Storage Tank: Some ultrapure water systems are equipped with flat-bottomed tanks. During maintenance, it's impossible to completely drain the water from the bottom of the tank. This residual water becomes a breeding ground for bacteria. Therefore, we recommend using a conical tank, which allows for complete drainage during maintenance, preventing bacterial growth.

2. Tank Material: Because ultrapure water is highly pure and virtually free of impurities, it easily absorbs contaminants from the external environment. If the storage tank is made of low-grade plastic, it is more susceptible to dissolving organic matter, increasing the water's conductivity and leading to a decline in water quality.

3. Disinfection: Even in a sealed environment, bacteria can proliferate, as even tiny microorganisms can form biofilms that contaminate the ultrapure water. Therefore, an ultrapure water system equipped with effective disinfection equipment is crucial.

4. Vent: Most ultrapure water systems have a vent to maintain pressure balance in their storage tank. However, this vent allows outside air to enter, introducing bacteria and particulate matter, which can contaminate the stored ultrapure water. Therefore, it is recommended to install a filter at the vent.

These are the reasons why ultrapure water quality may decline during storage. As you can see, proper storage of ultrapure water is crucial when using an ultrapure water system to minimize quality degradation. Additionally, some ultrapure water systems do not have a storage tank; they are used as needed, which also avoids storage issues.