The water that flows through mechanical Vehicle Wash Systems contains contaminants that can lead to the development of biofilm within the system pipework. This is before any consideration is given to the nature of the debris that the system has been designed to wash away. Typically, debris may include layers of mud, road grime and other constituents which can rapidly increase the contamination potential of the water system. Wash water is often recirculated at temperatures that are suitable for the growth of pathogenic bacteria. Vehicle wash systems designed to clean, unfortunately have the potential to infect operatives and bystanders with harmful bacteria, such as Legionella; causing infections such as Legionnaires’ disease and Pontiac fever.
This scenario applies to car washes, commercial vehicle washes and train wash systems. They all operate on similar principals and have the capacity for pathogen proliferation.
What Happens Next?
When a spray of water strikes a surface, small droplets of water (aerosols) are released into the atmosphere. These aerosol sized droplets can carry Legionella bacteria. It is the inhalation of these droplets that leads to the development of Legionnaires’ disease in humans. Aerosol drift (visable as a mist) from these devices is significant and can cover great distances. This is a recipe for disaster – a disaster that with due consideration can and should be avoided.
The potential risk is described in ‘Appendix One, Checklist 3: Other risks’, of the ‘Approved Code of Practice and Guidance (L8), the Control of Legionella Bacteria in Water Systems’.
Duty of Care
In general, these systems have been shown to present a potential risk to health and as such should be maintained in a clean state. They will often require regular disinfection and should be monitored on a regular basis where appropriate. There is a duty of care to carry out a risk assessment and to maintain records of all maintenance that is carried out together with monitored results.
For commercial wash systems a duty of care should be taken for both employees and others in the local environment; due consideration must be given to the surroundings – private dwellings, offices, retail outlets, etc. We only have to look at the Barrow in Furnace outbreak to see how widespread such an outbreak can become.
Whilst many of the detergent based products used greatly assist in the removal of the debris, their capacity for pathogen destruction is very limited, especially when facing organisms such as Pseudomonas, Legionella, and Coliforms.
Chlorine Dioxide 
Advances in Catalytic Chemistry mean that we can now generate and deliver safe levels of chlorine dioxide onsite directly at the point of application. This is achieved cost effectively and presents no risk of harmful effects to the vehicles being cleaned.
This technology is also used widely within the Healthcare and Food industry sectors as part of a managed Legionella control programme. Synergy with the operatives and the consumer is a vital key to the success of any biocidal treatment regime.
Safety First
Should your organisation operate a commercial Vehicle Wash System, it would be prudent to seek expert advice to review any potential risks to health it may present, and implement an operation / maintenance programme for legionella control where appropriate.
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