Legionella

While most commonly associated with cooling towers, Legionella, the causative organism of Legionnaires' disease, can be transmitted by other warm water systems, such as spas.

Aerosol-generating systems such as faucets, showerheads and nebulizers aid in the transmission of Legionella from water to air. Human inhalation of contaminated aerosols can lead to Legionella infection and disease outbreaks.

Although large piping networks are more conducive to the growth of Legionella bacteria than smaller systems, plumbing in houses and apartments still can harbor legionella bacteria.

This is why there are mandatory requirements in Victoria for maintaining and testing warm water systems, to minimise the risk of Legionnaires’ disease.
 
For further information on Legionella please refer to the Department of Health website: