Legionella Pneumophilia, more commonly known as Legionella , is a genus of pathogenic bacteria which is found naturally in freshwater environments, like lakes and streams. It is a harmless micro-organism when found in a natural settings, but not so harmless when it contaminates man-made water systems.



This particular bacteria is known to isolate itself to warm and moist environments where there is a continuous supply of nutrients from the sediment. Legionella proliferation is dependent on the pH of the water, and water temperatures between 25-55°c.

As mentioned above, Legionella bacteria is generally harmless when found in nature, but it can prove to be a threat to human health when they grow and spread in man-made building water systems like:

  • Showerheads & sink faucets
  • Cooling towers
  • Hot tubs
  • Decorative fountains and other water type instalments
  • Hot water tanks & heaters
  • Large, complex plumbing systems
  • Spa baths



After Legionella grows and multiplies in a building water system, water containing Legionella can spread in droplets small enough for people to breathe in. People can get Legionnaires’ disease or Pontiac fever when they breathe in small droplets of water in the air that contain the bacteria.

Less commonly, people can get sick by aspiration of drinking water containing Legionella. This happens when water accidently goes into the lungs while drinking. People at increased risk of aspiration include those with swallowing difficulties.



Now the question at hand is, why does this bacteria inhabit these man-made water systems in the first place? It’s quite simple – legionella bacteria is not well adapted to life in water systems, and often require protection offered by BIOFILMS.

The biggest threat to our existing  water systems is the ability of millions of bacteria to join together into a community. By working together, they are able to grow and reproduce faster, feed more easily, and protect themselves from half-hearted attempts to remove them.

Since biofilms provide protection to bacteria and are nutrient rich, it becomes a perfect breeding ground for legionella.

In addition to harbouring a number of bacteria, this biofilm also begins to eat into the pipework, and attach to scale and slime. Chlorine by itself is not powerful enough to remove this coat of slime – something much powerful is required.



The polysaccharide matrix – which is essentially the topmost layer of the biofilm, provides a tough protective cover for the large number of bacteria within. This layer cannot be penetrated or destroyed by convention biocides such as chlorine or sodium hypochlorite.

Only oxidising biocides like CHLORINE DIOXIDE can penetrate this layer and effectively destroy the biofilm.

Chlorine dioxide uses the oxidising capacity of the 2 oxygen molecules to completely destroy the cell membrane and nucleus. The oxidising process is so strong, that resistance cannot build up.

In addition to this, chlorine dioxide is also safe to use, non-toxic in nature, and approved throughout the world as a perfect biocide for drinking water applications. It’s effectiveness against a broad range of microorganisms and short contact time make it the perfect biocide for almost any disinfection application.



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