Legionella bacteria can cause the potentially deadly Legionnaires’ disease which is a severe form of pneumonia. Many health and safety experts have focused on the carrying out of a Legionnaires assessment as an essential first step in the risk management process in order to identify and then eliminate, or at least control the conditions associated with this bacteria.

Legionella bacteria exist in small quantities in many water systems, both natural and man-made. Any property that contains a water system is at risk of encouraging the growth of Legionella.

Why is testing for Legionella so important?

Outbreaks of Legionnaires’ disease can receive significant media attention especially when a large number of people become ill or die as a result of Legionella infections. In contrast to highly publicised outbreaks, single cases often go unnoticed or reported. However, Legionnaires’ disease is a legitimate public health concern as it can be fatal. The fatality rate during an outbreak ranges from 5% to 30% in those who contract the disease.

The immediate consequences for the building owner or manager faced with liability claims and negative publicity can be devastating and extremely costly. Many experts agree that proactively managing the risk of Legionella bacteria in the water systems is more cost-effective than responding to an outbreak after it has occurred.

Legionella pneumophilia can also cause a much less severe disease called Pontiac fever. Infection occurs when a person breathes in an aerosol (small droplets of water) containing Legionella. These aerosols are created by water striking a hard surface, water spraying from a showerhead or outdoor sprinkler system, “spritzer” cooling sprays, flushing toilets, and by air being bubbled through spa pools (jacuzzis).

It then stands to reason that testing for Legionella not only minimises the legal risks but also ensures that your business is kept in good standing publically.

How is Legionella Risk Managed?

The FCS risk assessment is a procedure that identifies potential risks that may be present in a workplace which can include an office, factory, school, hotel or hospital.

The assessment identifies potential dangers associated with this bacterium. This could be applicable to guests and customers in cases of businesses operating swimming pools and spas.

To understand why man-made water systems pose such a health risk, we must first understand what is required for bacteria to grow. Namely a food source, temperature, and time.

  1. A food source: Bacteria, like all living organisms, need a source of nutrients to enable them to grow. Legionella is able to grow on many different forms of “food” found commonly in artificial water systems. Slime, scale, dirt and rust often present in these systems all serve as food enabling Legionella to grow.
  2. Temperature: Bacteria require specific temperatures to enable them to grow. Legionella bacteria are known to grow optimally at temperatures between 20 and 45° Legionella is even known to survive temperatures as high as 50° Celsius.
  3. Time: Legionella needs time to grow to dangerous levels, however, they grow in an exponential fashion whereby 1 bacterium becomes 2, then 4, then 8, then 16 and so on. This allows them to grow to dangerously high levels in a relatively short amount of time.

All possible sources of Legionella are identified and water samples are taken for testing in our accredited Legionella testing laboratory. This is done to identify the presence of Legionella in a specific water source, should it be present.

Reducing the risk: A 15-point plan for reducing the risk from Legionella

  1. Have one named person responsible for Legionella control.
  2. Ensure the named person has sufficient training and experience to be able to carry out the role competently and other staff are trained to be aware of the importance of their role in controlling Legionella.
  3. Keep hot water hot and circulating at all times: 50°C – 60°C (too hot to put hands into for more than a few seconds) throughout the entire hot water system. Water to reach > 52° C within 60 seconds.
  4. Keep cold water cold at all times. It should be maintained at temperatures below 20°C throughout the system to all outlets (this may not be possible when the ambient temperature is high, but every effort should be made to ensure that cold water entering the premises and in storage remains as cold as possible). 25°C is the absolute max!
  5. Run all taps and showers in guest rooms and other areas for several minutes to draw through water (until it reaches the temperatures stated in points 3 and 4) at least once a week if rooms are unoccupied, and always prior to occupation.
  6. Keep shower heads and taps clean and free from scale.
  7. Clean and disinfect cooling towers and associated pipes used in air conditioning systems regularly – at least twice per year.
  8. Clean, drain and disinfect water heaters (calorifiers) once per year.
  9. Disinfect the hot water system with high level (50mg/l) chlorine for 2–4 hours after work on the system and water heaters and before the beginning of every season.
  10. Clean and disinfect all water filters regularly, as directed by the manufacturer, at least every one to three months.
  11. Inspect water storage tanks, cooling towers and visible pipework monthly. Ensure that all coverings are intact and firmly in place.
  12. Inspect the inside of cold water tanks at least once per year and disinfect with 50mg/l chlorine and clean if containing a deposit or otherwise dirty.
  13. Ensure that when carrying out system modifications or new installations they do not create pipework with intermittent or no water flow, and disinfect the system following any work.
  14. If there is a spa pool (also known as whirlpool spas, ‘Jacuzzis’, spa baths), ensure that:
    1. it is continuously treated with 2–3mg/l chlorine or bromine and the levels and pH are monitored at least three times per day;
    2. at least half of the water is replaced each day;
    3. sand filters are back-washed daily;
    4. the whole system is cleaned and disinfected once per week.
  15. Keep daily records of all water treatment readings, such as temperature, pH and chlorine concentrations and ensure they are checked regularly by the manager.

Food Consulting Services is a private South African-owned Food Testing Laboratory and Food Safety Consultancy, that tests water and food to ensure compliance with South African National Standards. We also perform hygiene survey audits to the hospitality and food manufacturing industry. If you’d like to learn more about Food Consulting Services, visit our website or feel free to enquire with us. We look forward to hearing from you and becoming your food safety partners. Get in touch with us for more information.

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