Hypochlorous acid is one of the most effective known biocides. This weak acid with the chemical name HClO or HOCl is the same chemical produced by the human immune system to kill invasive organisms and fight infection. It is a biocide so safe for humans and animals that we already have it in our bodies.
Hypochlorous acid is a highly oxidising solution that is bactericidal, virucidal, fungicidal and sporicidal. It is hundreds of times more effective at disinfecting than hypochlorite, but it is also, to all intents and purposes, non-toxic. Hypochlorous acid (the substance) has been known to man for literally hundreds of years and although a natural phenomenon, it can be replicated by dissolving acid into the water at a specific pH.
Once identified though, it is difficult to isolate and unstable. The alternative and to date, standard means of manufacturing Hypochlorous acid has been via the process of electrolysis. This entails passing an electric current through a brine in order to realize a limited quantity of Hypochlorous solution.
The process is not without its limitations: the electrolysis machines are extremely costly, they cannot make the solution in bulk, they only produce low strength Hypochlorous (up to 600ppm) and the machines are expensive to maintain, as the production process erodes the electrodes. Because of the saline origins, the resultant solution is also highly corrosive. The main limitation is the longevity of the product produced: it has a half life of between 48 and 72 hours, after which time it rapidly becomes benign. But after years of development, all this changed. In 2011 BHI* has managed the ‘impossible’ with its bold new method of production.