This is a classic "Achilles' Heel" of ultrapure water. The answer is a resounding no, you should not store it. Here’s why:

Ultrapure water is an incredibly aggressive solvent. Once produced, it immediately begins to re-equilibrate with its environment. In storage, it will:

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  Absorb Gasses: It rapidly absorbs carbon dioxide (CO₂) from the air, forming carbonic acid and dropping the resistivity significantly.

  
  


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  Leach Contaminants: It can dissolve ions from the storage container itself (even from high-purity plastics like PFA or PP).

  
  


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  Support Microbial Growth: Without a constant purge, bacteria can colonize the storage tank and produce endotoxins and organic impurities.

  
  

For these reasons, UPW is always best used "on-demand," directly from the point-of-use dispenser, to guarantee its pristine quality for your critical applications.

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