On tap – a sustainable sanitiser

Published: 22-Jun-2010

The knowledge that electrolysed water could be a sanitiser has been around for years, but Japanese scientists have turned the idea into a simple and cost-effective sanitisation process, as Laurence Bailey, md of UK distributor EOwater, explains

The knowledge that electrolysed water could be a sanitiser has been around for years, but Japanese scientists have turned the idea into a simple and cost-effective sanitisation process, as Laurence Bailey, md of UK distributor EOwater, explains

To find a product that is effective at reducing bacteria and viruses, safe for use in public areas, requires a short contact time and is also low cost, is the ambition of every infection control professional.

The chemical industry has reformulated and repackaged its ever-increasing product range over the past 50 years in its attempts to satisfy the constantly changing demands of infection control practitioners. However, behind the shiny new packaging and marketing campaigns, there is really little in terms of true chemical development.

In the 1960s, Russian scientists began development of a commercial application for water electrolysis. There was clear evidence that this technology could offer something that, up until then, had not been available. Early testing showed it to be a very effective and, potentially, low-cost means of killing bacteria. Unfortunately, the technology proved difficult to harness, especially on a scale that was necessary to realise its cost efficiency.

Some 30 years later, several Japanese companies reassessed the technology and, using their nation’s aptitude for electronics, succeeded where the Russians had failed. One of the most prominent companies involved was the Hoshizaki Electric Company, which quickly began producing cost-effective production units with minimal footprints under the brand name ROX, derived from Reduction OXidation.

With Hoshizaki’s reliability behind it alongside its sheer production flexibility and cost efficiency, ROX has sold widely across the food production and healthcare industries throughout Japan. The system is now available in Europe and specialist distributor EOwater is driving the market development in the UK for Hoshizaki.

Water electrolysing is not in itself new, of course, but an easy and reliable method of harnessing it on demand has not been available before. ROX’s technology starts by cleaning tap drawn water and adding salt to produce a saline solution. This solution is then electrolysed, causing it to change into two new entities, one alkaline, the other an acid.

The alkaline entity is a 1% solution of sodium hydroxide while the acid is a 0.1% solution of hypochlorous acid. The alkaline fluid is a useful cleaning solution, however the acidic water is a potent sanitiser.

Hypochlorous acid is a common by-product of the breakdown of chlorine-based chemicals and is found in the breakdown of common bleach (sodium hypochlorite). It is highly unstable and, once in an open atmosphere, will very quickly release chlorine, rapidly reducing its efficacy. Although there are many other active antibacterial properties associated with hypochlorous acid, chlorine is an important element. Irrespective of the method used to produce hypochlorous acid, it will have the same properties – the rapid release of chlorine being one.

For a commercial chemical manu-facturer, producing hypochlorous acid is not financially viable. Its shelf-life is extremely short, meaning production runs would have to be small and frequent. Deliveries to customers would have to follow suit.

From the customer’s viewpoint, systems to check use-by-dates would have to be implemented, stock levels would have to be closely monitored and, because of the short shelf-life, a high wastage allowance would have to be built in. As a result, hypochlorous acid is not available to purchase. The Hoshizaki ROX, however, enables it to be made on site and on demand.

EOwater designs the optimum system for every site with as many user access points as required. Because the hypochlorous acid is only drawn off as needed, there is no wastage in terms of quantity. At the time it is drawn off, its efficacy is at its most potent level, so there is no compromise on quality. The customer also has the option to store it in opaque spray bottles where it will remain effective for a minimum of seven days.

Once used, the product can be safely discharged to the main drain without effect.

Bespoke systems

ROX systems are designed on a case-by-case basis to reflect customers’ demands, from simple over-the-sink production units to systems with more than 600 litres of storage and the capability to produce more than 4,000 litres of both acidic and alkaline water per day. Numerous units can be combined for unlimited production and unlimited storage. In Japan, where many systems are in use, it is common to find a small, single outlet ROX unit in a café or restaurant and complex configurations serving major food production units.

The acidic water is designed to be used as part of a hand wash system and, in Japan and the US, is approved as a “Food Additive”. This clearly indicates that it is a low hazard product that is safe to use and to come into contact with skin. It is not even harmful if accidentally ingested.

Because it is completely safe, it can be used in public areas without risk – even when human contact is likely.

The process of killing bacteria is usually achieved within seconds, with common bacteria such as MRSA dying in just five seconds. Because of its unstable nature, the chlorine dissipates almost instantly, leaving no residue. In the case of hand washing, within seconds of drying hands there is no smell of chlorine. The speed of the process prevents bacteria and viruses from developing immunity, so using ROX in place of standard chemicals means that it will always be effective and also eliminates the need for brand alternating.

In the case of pandemic planning, as the product can be relied upon to be effective at all times (with no immunity issues as found with manufactured alternatives) any quantity can be drawn off on demand as long as water, electricity and salt are available. There is, therefore, no need to hold reserves of chemical stock. If a sudden outbreak of infection were to occur, ROX can simply be used more liberally and more frequently.

When a ROX system is installed there is no financial advantage to the supplier whether the customer produces large or small volumes of product. Unlike traditional chemical cleaners and sanitisers, where increased demand means larger orders, there is virtually no more revenue generated from greater use of ROX equipment. In fact, when all costs are considered as a capital project, to include finance, water, electricity and salt, the average cost per litre for a standard installation is only 2p.

As part of its commitment to research and development, Hoshizaki has supplied ROX equipment to various universities around the world to encourage independent research. This has resulted in much published scientific evidence to prove that it does work as stated.1, 2, 3

The electrolysed water can be used to clean and sanitise various foods, hands and surfaces

The electrolysed water can be used to clean and sanitise various foods, hands and surfaces

Essentially, all the research concludes that acidic water kills a wide range of bacteria and viruses, is safe to use and leaves no residue. It has been shown to have beneficial effects when used to clean fruit and vegetables in that it extends its shelf-life, has no adverse effect on the quality of the foods it is used to wash and brings big benefits to fish and shell fish that are to be eaten raw.

Why it is so effective so quickly is something that the researchers, as yet, cannot agree upon. It is agreed, however, that bacteria and viruses are killed by ROX water and that there are three main components of the effectiveness: chlorine content (around 80ppm), oxidation reduction potential (ORP more than 1200mv) and pH (around 2.8).


1. Kim et al, 1.11.2000, Int. J. of Food Microbiology, Vol 61, (2–3), p199–207.

2. Fabrizio et al, Poultry Science, Vol 81, (10), 1598–1605.

3. Koseki et al, J. Food Protection, 2001 May 64 (5) p652–8.

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