Many public buildings and accommodation facilities such as fitness centres, swimming pools, schools and hotels are closed until at least the end of January or even longer. Due to stagnating water, unused water systems are now at an increased risk of Legionella growth. Therefore, drinking and other water systems need to be monitored and managed even more closely at this time.
What are Legionella, how do they grow and how dangerous are they?
Legionella are bacteria that naturally occur in fresh water reservoirs such as surface or ground water. That is why they are present in drinking water, albeit in very small numbers. At temperatures of 25 to 45° Celsius Legionella can start to propagate quickly and to great numbers in man-made water systems. Stagnating water in unused pipes or other systems further promotes Legionella growth. It is, however, possible to avoid heavy contamination if you observe legal regulations (may vary depending on your location) and all recommended technical guidelines.
An infection with Legionella can occur when water is nebulized into tiny droplets and Legionella-containing aerosols develop that are inhaled by humans. Potential sources for infection are:
- Fountains or whirlpools in wellness areas
- Mist humidifiers and mist cooling systems
- Air conditioning, cooling towers and evaporative cooling systems
- Decorative (indoor) fountains, water walls or curtains
In the event of an infection, 2 to 10 days after exposure to Legionella flu-like symptoms develop that turn into a severe lung infection (pneumonia). The disease is referred to as legionellosis or Legionnaire’s disease. A relatively high number of patients need to be treated in hospital but there are effective antibiotics against legionellosis. Nonetheless, the mortality rate of 5-10% is quite high. In Europe, the number of reported cases has steadily increased over the past years but varies greatly between countries due to differences in monitoring the disease (figure, source: ECDC).
Figure 1: Cases of Legionnaire's disease in the EU/EEA from 2007 to 2018 (ECDC).
How can you avoid Legionella growth during lockdown?
To reduce the risk of Legionella growth, drinking water pipes and heaters, swimming pools, spa pools and other water sources at risk need to be managed and monitored carefully. After a longer period of low use or disuse, legal regulations for taking water systems back into operation need to be observed before re-opening the facility. This will help to reduce the risk of infections. Preventive measures include:
- Stagnating water promotes microbial growth. During lockdown (gently) flush all outlets of hot and cold water separately (at least once a week) until the water reaches the below mentioned temperatures. Also, flush WC cisterns, urinals and any other points on the network.
- Cold water should be maintained at a temperature below 20° Celsius and hot water should be maintained at a temperature above 50° Celsius to avoid ideal growing temperature for bacteria.
- Solid deposits such as scale, corrosion products or biological deposits (biofilm) can also promote the growth of Legionella. Therefore, remove deposits in pipes, storage tanks, heaters or pools by applying appropriate, professional cleaning agents.
- Clean and disinfect warm water storage tanks, heaters or boilers at regular intervals and additionally before re-initiating normal operation after a period of disuse.
- Disinfect pool water continuously, measure pH several times a day. Empty pools and clean them with professional cleaning agents and devices (such as low pressure spray systems) at least once a week.
- Filter systems in swimming and spa areas need to be back-flushed at regular intervals.
Before reopening, it is recommended to undertake microbiological sampling to ensure that Legionella are not detected above allowed levels.
What can you do in case of increased numbers of Legionella?
Should Legionella be detected despite implementing preventive measures, please make sure that all legal requirements (may vary depending on your location) are met. To efficiently remove Legionella from pipes, water storage tanks or pools clean, flush and disinfect them with appropriate cleaning agents and disinfection products that are specific to your application. This will ensure complete removal of the harmful bacteria that generally accumulate in biofilms. Depending on the application, you may want to consult a specialist company. For the removal of Legionella from drinking water pipes CARELA developed a multi-step cleaning and flushing procedure (multi-step flushing) that first breaks open the biofilm and subsequently removes it from the internal surfaces. After completing these measures microbiological samples need to be taken and analysed to verify their success.
CARELA GmbH offers professional cleaning and disinfection products and services for all types of drinking water and other water systems as well as comprehensive guidance on drinking water hygiene and prevention of Legionella. CARELA also carries out risk assessment of your water system should you require it.
How can we help you? Call (+49 7623 7224 0) or email us today to hear more on our products or services!
- European Centre for Disease Prevention and Control (2016). ECDC Health Information: Information about Legionnaire’s disease for managers of tourist accommodation.
- European Centre for Disease Prevention and Control, Surveillance Report. Legionnaires’ disease: Annual Epidemiological Report for 2016 and 2018; and Annual epidemiological report: Reporting on 2011 surveillance data and 2012 epidemic intelligence data (2013).
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