Lockdown could lead to an increase in waterborne pathogens such as legionella bacteria

The impact of COVID-19 has had far-reaching effects. As we slowly return to the new normal, we are seeing a number of new challenges. One in particular is that of the management of legionella, with buildings laying mostly dormant for weeks. Testing regimes have been difficult to maintain due to lack of available services and restricted access to closed buildings; these conditions could lead to an increase in waterborne pathogens such as legionella bacteria.

Legionnaires’ disease is a type of pneumonia, which can cause serious respiratory illness and death. It occurs when inhaling fine drops of water, known as aerosols, containing legionella bacteria. Aerosols could be circulated by air conditioning units, or found around taps and showers where there is a build-up of scale restricting water flow.

It is worth highlighting that due to the COVID-19 pandemic, an increased number of people could be more susceptible to Legionnaires’ disease due to a compromised respiratory system during or after infection with COVID-19.

Employers and people in control of premises, such as property owners, have a duty to protect people by identifying and controlling risks associated with legionella.

If your building has been closed or had reduced occupancy during the COVID-19 outbreak, water system stagnation may have occurred due to lack of use, increasing the risks of Legionnaires’ disease.

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

  • Reinstate a water system and start using it again.
  • Restart some types of air conditioning units.

Insurers might limit Legionnaire’s coverage amounts or impose higher deductibles if building systems are outdated. Insurers may also be stepping up their scrutiny even more due to the coronavirus pandemic, making it important to follow and implement key steps when considering re-opening.

Advice for Re-Opening

Essential steps for managing the risks associated with legionella bacteria include:

  • Undertaking a risk assessment.
  • Establishing controls and a management plan.
  • Implementing, monitoring, and reviewing regularly.

If you have already reviewed your risk assessment and implemented additional control measures, then it is unlikely you will need to take any further steps prior to reopening.

It is reasonable to assume that where buildings have been unoccupied for a number of weeks there will have been an increase in bacterial growth and as such the system will need to be managed before it is put back into use.

Where no additional action has been taken, or you are concerned about the effectiveness of controls implemented, you must take reasonable steps to ensure the safety of the water system prior to reopening.

Steps to take prior to reopening could include:

  • Flushing through simple hot/cold water systems with fresh mains water for several minutes.
  • Increasing the temperature of hot water systems to above 60°C if possible and drawing the heated water through to all hot water outlets (a temperature over 60°C will kill Legionella bacteria over time).*
    * Increasing the water temperature to 60°C and above can result in a scalding risk. While water should be stored at 60°C, there should be a thermostatic mixing valve before the tap to reduce the temperature to around 43°C.
  • Flushing through larger hot/cold water systems (including those with tanks, showers, clarifiers etc.) for a significant period of time.
  • Ensuring that the system is capable of delivering water at safe temperatures by checking temperatures ahead of reopening.
  • Undertaking a chemical or thermal disinfection of the water system.
  • Undertaking microbiological sampling for Legionella bacteria.

Guidance on the management of Legionaries’ disease is contained within the guidance document L8 (fourth edition), which is available as a free download from the HSE, or the most recent guidance from the CEIH, ”Legionella risks during the coronavirus outbreak”.

Please note that each individual water system within a building or workplace is likely to need some degree of individual consideration as no two systems are entirely alike. Additionally, some systems believed to be under good control may now show that previous high levels of use and turnover have masked existing issues; these could become apparent during periods of low use.

Darren Holmes is senior vice president at Marsh Advisory