Sustainable disinfection with hypochlorous acid (HClO)

What is hypochlorous acid?

Hypochlorous acid, also known under the scientific formula as HClO, is a very weak acid. However, it has oxidizing properties and is, therefore, widely used as a disinfectant. It is effective against bacteria, fungi, and viruses.

Where can hypochlorous acid be applied?

Hypochlorous acid has a wide range of applications, where disinfection and hygiene are of high importance. It is used, for instance, in the treatment of process water (e.g. in the food industry), disinfection of the drinking water supply for farm animals or for legionella and biofilm control in medical facilities. You can discover all the applications at www.watter.nl/en/applications/.

Healthcare sector

Farming sector

Industrial sector

How is hypochlorous acid produced?

Hypochlorous acid is produced with the use of a technology called electrochemical activation (ECA) by the electrolysis of water containing dissolved sodium chloride (salt).

How effective is hypochlorous acid?

Hypochlorous acid is the most effective disinfectant in the chlorine family available in dilute solution.

What is the difference between hypochlorous acid (HOCl) and sodium hypochlorite (NaOCl)?

Sodium hypochlorite (NaOCl), which is household bleach, is formed from chlorine (Cl) and sodium hydroxide (NaOH). The names and scientific formulas of hypochlorous acid and sodium hypochlorite sound very similar, however, these are two different substances. The biggest difference can be seen in the effectiveness: you need a lot more bleach (sodium hypochlorite) to achieve the same anti-microbial power as with the use of hypochlorous acid.

A more detailed comparison can be seen in the table below:

Equilibrium chart on chlorine in solution

Available chlorine 10-30 ppm, pH 4.0 - 7.0

The above graph presents how chlorine composition changes according to pH value in three phases of Cl2, HOCl and OCl-. A lot of HOCl can be formed if the pH of water is between 4.0 and 7.0.

Since HOCl (hypochlorous acid) has been proven to be the main disinfectant, it can be, therefore, used for effective disinfection, although the chlorine concentration is only 10-30 ppm.
On the other hand, a sodium hypochlorite solution contains only about 5% of hypochlorous acid, which means that a very high chlorine concentration of around 100 to 200 ppm should be used. The remaining 95% is OCl-, which has a very low bactericidal effect, remains unused and will be discarded in wastewater.

Hypochlorous acid - the natural disinfectant

Hypochlorous acid is also produced in the human body by white blood cells to fight infection by acting against a wide range of microorganisms. It is an important part of the innate immune system. This acid has a bactericidal effect and immediately destroys bacteria. Despite its high biocidal activity, hypochlorous acid is not cytotoxic to human and animal cells.

Interested in responsible disinfection?

Watter® Hand Sanitiser and Watter® Surface Disinfectant do not contain alcohol, perfume, aldehydes, parabens, dyes or any substance identified as carcinogenic. Our products are hypo-allergenic, non-irritating to the skin, eyes or lungs, and do not produce any toxic vapour.

Learn more