Sources of legionella in commercial buildings other than water systems

Microbacterial growth is not only a problem in hot and cold water systems and cooling towers but also in many other applications in commercial buildings such as water fountains, spas, swimming pools and fruit and vegetable moisturising systems.

Common for the below mentioned systems are that legionella grows often in the water and aerosols easily are dispersed to the surroundings. The aerosols can be breathed into the respiratory system, causing risk of Legionella disease or Pontiac fever. All the systems should be provided with effective water disinfection systems, which are able to remove both biofilm and kill free bacteria and other microorganisms. 

Water fountains:

Water fountains in shopping malls, airports, hotels, fun parks are subject to bacteria growth. Water is sprayed into the air and airborne droplets are formed and are easily inhaled into the lungs of the guest.  Fountain water is the same temperature as the surrounding air 25 – 35 C. At that temperature legionella and other bacteria grow easily in the water and biofilm. 


Legionella are a particular problem in spa baths because the water is at an optimum temperature for the legionella bacteria to grow and because dirt, dead skin cells etc. from the people using the bath provide food for the bacteria. Furthermore the piping for the air and water circulation provides a large surface area for the bacteria to grow on.

The agitated water in spas forms aerosols in which legionnella bacteria can be contained and breathed into the human lungs.

Fruit and vegetable moisturising:

In order to maintain fruit and vegetables fresh as long as possible water is sprayed into the air in many groceries and supermarkets. This procedure is not only able to reduce moisture- and weight loss of fruit and vegetables also promote re-hydration.

Re-hydration enables fresh produce to regain the moisture already lost since harvest and therefore extend fruit and vegetable life dramatically.