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Covid-19 and managing legionella risks

close up of legionella bacteria

Employers and anyone in control of premises (including landlords/hotels/schools) that use purpose-built water systems, have a responsibility to control the risks of exposure to legionella

An individual can catch Legionnaires’ disease, a potentially fatal illness, by breathing in small droplets of water containing the bacteria, usually when bacteria has got into the water supply. For example, it can be caught from air conditioning systems, shower heads & taps, as well as spas and hot tubs. 

The bacterium Legionella pneumophila and related bacteria are common in natural water sources such as rivers, lakes and reservoirs, but usually in low numbers. They may also be found in purpose-built water systems such as cooling towers, evaporative condensers, hot and cold water systems and spa pools.


Increased legionella risks as a result of lockdown

Lack of use of a water system, whether a building has been closed or at limited capacity, can cause water stagnation, which increases the risks of Legionnaires’ disease. This could affect offices, hotels, restaurants and even schools where closure or part closure has been a result of the Coronavirus lockdown.

Whilst businesses have been in this prolonged period of closure or limited use, it is important to recognise that the health and safety responsibilities of employers still remain. As part of your return preparations you should be mindful of any issues that could arise or pose a risk to returning employees or individuals, yet in the case of legionella risks you should have measures in place to maintain water systems. A competent person must be appointed to carry out the risk assessment and any control measures. The HSE recognise that it may be difficult to seek specialist help during the current circumstances, so in the case of not being able to appoint someone you should consider stopping operation of the water system.

Maintenance and monitoring should be done by someone who has the proper training to do it. It must be done by someone who understands your water system and the equipment which makes it up. But it’s the person who is in control of the premises who is responsible for making sure it is done, for making sure systems are regularly serviced, making sure reports are kept up-to-date and for making sure risks are kept as low as they can practicably be.

iHASCO’s online Legionella Awareness Training

Review your legionella risk assessment

You will most likely already have a risk assessment, which can be reviewed, to enable you to manage the legionella risks once you have reopened and the water system is back in full use. Equally if the water system has been used regularly ensure you are continuing to follow preventative measures to protect from the risk of legionella exposure. 

The HSE has identified additional steps that can be taken to manage the risk of legionella during the Covid-19 pandemic, which includes:

  • Flush hot and cold water outlets weekly to prevent water stagnation, if they are used infrequently. In cases where this cannot be carried out ensure systems are cleaned and disinfected before the building becomes occupied.
  • For Cooling towers and evaporative condensers, before shutdown, operations should have already been reviewed to ensure plans are in place for carrying out essential checks and monitoring, as well as maintaining and dosing chemical supplies appropriately. These must be carried out by appointed individuals who have been adequately trained. In the case of stopping the operation of any water systems contact your water treatment company for advice. 
  • Where cooling towers and evaporative condensers are not in operation take appropriate measures. Where operation will cease for up to a month, isolate fans but circulate biocidally-treated water around the system for at least an hour each week. If use is likely to be out for over a month drain down the system, clean and disinfect it. Before refilling and returning to operation you should clean and disinfect the system.
  • In the case of commercial spas and hot tubs where they are not in use, drain, clean and disinfect them. Before refilling they should be cleaned and disinfected again.

If you are changing any control measures you need to be aware of any further risks these could pose and detail them on your risk assessments. You should also make sure you have the correct PPE for any water systems that require cleaning to provide adequate protection.

For further guidance you can access the HSE page Legionella risks during the coronavirus outbreak or 

The Chartered Institute of Environmental Health guidance on Legionnaires’disease: lockdown risks and reopening safely.

Online Legionella Awareness training 

It is important to not only understand how to control the risks of legionella bacteria and meet health and safety requirements, but also know where it can be found and how it spreads. iHASCO’s 25 minute online Legionella Awareness training is suitable for those who are responsible for protecting an organisation from this kind of bacterial contamination but also for all employees, so they too can recognise the symptoms of Legionnaires' disease and understand the part they can play in protecting your organisation from it.  

iHASCO's online legionella awareness training course