What are legionella and how do they form?

Legionella is a genus of bacteria found in natural bodies of water such as lakes and rivers. They were first identified in 1976 when an outbreak of Legionnaires’ disease (legionellosis) occurred. The disease can cause severe pneumonia and is particularly dangerous for the elderly, smokers and people with weakened immune systems.

In low concentrations, legionella generally pose no danger. However, under optimal conditions, a single legionella bacteria can multiply to 65,000 within 48 hours. If a certain threshold value is exceeded, there is cause for concern. Infection with Legionella usually occurs through inhalation of water in the form of aerosols (steam baths, bubble baths, showers and toilet flushing), less frequently through ingestion (aspiration into the respiratory tract).

Formation of biofilms in water pipes

Legionella can also colonize and multiply in clean tap water. This often happens in warm stagnation areas of water pipes, especially at water temperatures between 25 and 45 degrees Celsius. A critical aspect in the proliferation of legionella is the formation of so-called biofilms in the water pipes.

What are biofilms?

Biofilms are complex associations of microorganisms that adhere to surfaces (inner walls of water pipes, shower hoses) and are protected by a mucus-like matrix of polysaccharides, proteins and other substances. This matrix makes the microorganisms more resistant to measures such as flushing.

Favoring factors

The formation of biofilms and the proliferation of legionella is favored by the following factors:
  • Material of the pipes: Certain materials such as plastic offer microorganisms better adhesion than others.

  • Stagnation: Stagnant water offers microorganisms the opportunity to multiply and form biofilms.

  • Temperature: Warm water between 25 and 45 degrees Celsius promotes the growth of biofilms and legionella.

  • Nutrients: Even minimal amounts of organic material in the water can support the growth of biofilms.

Measures to prevent the formation of legionella

An infection with legionella is extremely dangerous for the elderly, smokers and people with a weakened immune system. Buildings such as hospitals and nursing homes are therefore particularly required to take prophylactic measures to prevent contamination of the tap water. There are various measures to prevent the formation of legionella in water pipes:
  • Regular maintenance and cleaning: Regular inspections and cleaning of water pipes and water tanks can help to minimize the formation of biofilms.

  • Temperature control: Keep the water temperature above 60 degrees Celsius in hot water systems to kill legionella and below 20 degrees Celsius in cold water systems to inhibit their growth.

  • Flushing the pipes: Regular flushing of the water pipes, especially in rarely used areas, prevents stagnation and reduces biofilm formation.

  • Avoid piping dead legs: Dead legs in which the water stands for a long time and does not circulate should be avoided or flushed regularly.

  • Disinfection: WATER DISINFECTION Plus is approved for the disinfection of tap water and drinking water. The water disinfection solution reliably kills germs even at low concentrations. When used continuously, the solution breaks down the biofilm in the water pipes and effectively prevents contamination with harmful (pathogenic) germs. Renewed biofilm formation is virtually impossible.

    The simple integration into existing dosing systems enables cost-effective and sustainable disinfection that is odorless and tasteless. The product leaves no residue in the water and enables continuous dosing without hesitation, so that clean and germ-free water is always available without having to compromise on safety.

Summary: Legionella poses a significant health risk, especially in larger buildings with complex water supply systems. By better understanding biofilm formation and implementing preventative measures, the spread of dangerous bacteria can be effectively controlled. A proactive approach to the maintenance and servicing of water supply systems is crucial to ensure health and safety. A water disinfection solution from Hydroliq can help.