How long will my hypochlorous acid last?

How long will my hypochlorous acid last?

Bleach is notorious for losing its disinfecting strength after 24 hours of mixing with water. But what about hypochlorous acid? How stable is the hypochlorous solution you generate in a machine?

All chlorine-containing solutions are unstable by nature. Chlorine atoms have unpaired electrons and thus are constantly searching for an electron to bond with. This is what makes them oxidizing agents.

When hypochlorous acid is generated, the available electrons head out in search of other molecules (electrons) to attach to and oxidize. This is how hypochlorous works as a disinfectant, but as these electron pairs form, the amount of free available chlorine also decreases. Therefore, the more organic material present in your water or the container holding the hypochlorous, the shorter its "shelf life" will be. 

It's also important to keep hypochlorous in an opaque container, if possible. Exposure to UV light splits chemical bonds, breaking down HOCl into hydrochloric acid and oxygen. Keeping hypochlorous acid at room temperature can also extend its life. At temperatures above 77 degrees Fahrenheit (25 C), HOCl begins to degrade.

While we cannot guarantee a specific shelf life for the solution you make in the Hypo 7.5, when following the prescribed practices listed below, we've found no degradation for 2 weeks and low degradation for several months.

Tips to keep your hypochlorous acid stable for longer:

  • Keep it in a cool room
  • Use an airtight container
  • Generate using clean water
  • Avoid direct exposure to high temperatures and sunlight
  • Make a hypochlorous with a high ppm (free available chlorine content)



ISHIHARA, M., MURAKAMI, K., FUKUDA, K., NAKAMURA, S., KUWABARA, M., HATTORI, H., FUJITA, M., KIYOSAWA, T., & YOKOE, H. (2017). Stability of weakly acidic hypochlorous acid solution with microbicidal activity. Biocontrol Science, 22(4), 223–227.

Photo by Hans Reniers on Unsplash

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