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26/07/2021- Reminder for businesses to check water systems to prevent risk of legionella

Public Health England are advising businesses to make sure they check their water supplies and water management processes due to an increased risk of Legionella bacteria being present as a result of water systems not being used whilst premises have been closed during the recent lockdown.

Employers, the self-employed and people in control of premises, such as landlords, have a duty to protect people by identifying and controlling risks associated with legionella.

If your building was closed or has had reduced occupancy during the coronavirus (COVID-19) pandemic, water system stagnation can occur due to lack of use, increasing the risks of Legionnaires’ disease.

Legionnaires’ disease is a lung infection, caused by inhaling small droplets of water, suspended in the air, which contain Legionella bacteria. It’s uncommon but can cause serious illness which can usually be treated with antibiotics, but because symptoms are similar to those for Covid-19 people may not realise they have been infected. Symptoms of Legionnaires’ disease include a high temperature or fever, a cough, along with muscle pains, a headache and sometimes pneumonia. People who are feeling unwell with similar unexplained symptoms should ring NHS111.


As more and more businesses have recently reopened and people are returning back into office spaces, we are reminding you of the need to make sure your  water system has been reviewed to ensure it is safe for your employees and customers.

You should review your risk assessment and manage the legionella risks when you:

  • reinstate a water system or start using it again
  • restart some types of air conditioning units
  • If the water system is still used regularly, maintain the appropriate measures to prevent legionella growth.


All water systems need to be considered. This includes water systems at shops, hairdressers, offices, hotels, gyms, sports clubs, golf clubs, hotels, pubs, clubs, restaurants, voluntary-run premises and anywhere that has a water supply and was recently closed.

Anyone who manages or own buildings must follow the latest advice from the Chartered Institute of Environmental Health and the Health and Safety Executive to help minimise the risk from legionella.

You should implement a suitable weekly flushing regime using fresh mains water as follows:


  • Flush through simple hot and cold water systems with fresh mains water for several minutes.


  • Increase the temperature of hot water systems to above 60°C if possible and drawing it through to all hot water outlets (a temperature over 60°C will kill Legionella bacteria over time)


  • If you have a business in which showers are in use, you should also clean the shower head regularly. This doesn’t just mean the parts you can see, you should dismantle the shower head and clean it both inside and out with a recognised product to help combat any scale, debris or bacteria.


  • Flush through larger hot and cold water systems (including those with tanks, showers, calorifiers) for a significant period of time


  • Ensure that the system is capable of delivering water at safe temperatures by checking temperatures ahead of reopening


  • Undertake a chemical or thermal disinfection of the water system or microbiological sampling for Legionella bacteria if required.


If the building has been unused for a long period of time, there have been any lapses in flushing regimes or where additional risks have been identified, professional cleaning and disinfection may also need be undertaken.


Further details on Legionnaires’ disease, the type of workplaces which may be at most risk and details of how to carry out risk assessments can be found on the Health and Safety Executive website at or from the Chartered Institute at

Source: Public Health England