Legionella Awareness


With the cleaning industry being one of the biggest users of water, the risks that contaminated water poses are quite significant with substantial impact on the environment and users.


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Specialised Cleaning
April 11, 2017
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Legionella Awareness

With the cleaning industry being one of the biggest users of water, the risks that contaminated water poses are quite significant with substantial impact on the environment and users. One of the biggest risks comes from a pathogenic group of bacteria called Legionella. With over 70 sero groups and 45+ species, it includes L. pneumophila, which causes Legionnaires’ disease and L. longbeachae, which causes Pontiac Fever. Legionella live within water, in the natural environment and are harmful to humans through inhalation of water droplets (aerosols).

Risk & repercussions

Legionnaires’ disease can be fatal, while Pontiac fever – although less fatal - affects the respiratory system. Overall, the mortality rate from Legionnaires’ disease is 10-15 per cent of those who have symptoms. The most susceptible are males over 45 years, smokers, organ transplant patients, people with weakened immune systems. It is however important to remember that anyone can contract Legionnaires disease.

Legionnaires’ disease can lead to death if not diagnosed or treated correctly; case studies show that some patients can live with longterm complications like breathing issues, susceptibility to lung infections and a weakened immune system are just a few long-term problems reported.

Main sources & prevention

Legionella bacteria are found in the natural environment, i.e., lakes, rivers and reservoirs. It becomes a high risk to humans when it enters the artificial water air conditioning systems, cooling towers and contaminated hot and cold water systems, including swimming pools, spa pools, water features/fountains, domestic water (showers being the highest risk), irrigation systems and any water system or outlet with water likely to exceed 20°C and that may release aerosols during operation or maintenance.

Although the bacteria cannot be eliminated completely, it is easy to control by adopting good practices.

  • Water temperature cold water < 20°C and hot water >50°C at the output and stored at > 60°C
  • Regular tank cleaning - it is recommended to have this carried out twice a year on all water tanks.
  • Chemical treatment or alternative treatment and monitoring to ensure that the limits are met and treatment is effective.
  • Ensure that there are no dead ends (any outlet that is unable to be drained), dead legs (an outlet that is not used in over one month) or little used outlets, which are not used in over 1 week. If these are found in your property, they should either be removed to the main pipe or put onto a flushing schedule and flushed weekly, and it’s important that a record is kept.
  • Showerheads should be removed and disinfected with a chlorine-based solution on a 3-monthly basis; it is also important to ensure that all faucets are kept clean and clear of rust.
  • Swimming pools and water fountains should be regular cleaned of debris and chlorine or alternative chemicals should be monitored and maintained to the recommended levels.

Post infection actions

If there has been an outbreak of Legionella bacteria, you should follow your emergency plan, which has been implemented by the person/persons responsible for legionella control. This person or persons should have undergone training in Legionella awareness. Your risk assessment will contain the communications procedure and contact details for the relevant persons.

An emergency decontamination will be carried out per protocol, water samples should be collected before and after decontamination and sent to an approved laboratory, the person in charge of the premises should immediately submit a report to the Dubai municipality/ Public health and safety department contact centre on 800900 within 24 hours.

Emergency disinfection can be carried out by a chemical solution, which is the best method in cold water systems or thermal disinfection, which can be used in hot water systems. This should be carried out by trained professionals following the Dubai municipality guidelines. Both forms of treatment will kill the bacteria by deforming the bacteria’s structure and therefor eliminating the bacteria from being harmful to humans and ensuring a clean water system.

Risks to look out for

Cleaning and soft FM attendants should be made aware of the importance of the risk areas so they are able to work with the engineering department and with the management in identifying risks and eliminating them. It is everyone’s responsibility to ensure that procedures are followed, records are kept and risks are identified and reported in order to control Legionella in the air cooling systems and hot and cold water systems.

About the Author: Laura - Jane Lee is the Managing Director at H2Ology. H2Ology provides Legionella awareness training and risk assessments on all property types.