Legionella: managing the risks and reopening safely

The HSE has issued advice concerning the increased risks of legionella arising from lockdown. This is caused in particular by closed or reduced occupancy of buildings. Employers, the self-employed and people in control of premises, such as landlords and tenants, have a duty to identify and control risks associated with legionella.

It is essential that when buildings begin to re-open after lockdown that the risks are assessed before water systems are put back into use. All hot and cold water systems must be considered; anywhere that has a water supply which is currently shut down or is experiencing restricted use poses an increased risk. That includes offices, hotels, retail outlets, hairdressers, beauty salons, gyms, sports clubs, golf clubs, pubs, clubs, restaurants, camp sites etc. There is separate guidance available for swimming pools, spas, schools and complex water systems.

The Chartered Institute of Environmental Health reports that a combination of warmer external temperatures and low use of water systems has created ideal conditions for legionella bacteria to grow. Legionella bacteria thrives between 20 and 50 degrees; one of the key control measures is to ensure your cold water is cold and your hot water is hot. The time for stagnation has increased across buildings unoccupied or with reduced use. Generally where water is left within a system without movement for more than a week then the risk of growth will increase.

What do organisations need to do? Organisations must continue to take steps to manage the risks of exposure to legionella. This includes a suitable and sufficient risk assessment and where the risks within the water system have changed, as they have now for a large number of systems, the risk assessment must be reviewed and revised. For simple hot and cold water systems, a review should be straightforward. The main focus is to prevent stagnation and avoid water temperature in the risk area of 20 – 50 degrees. Guidance published by the Chartered Institute of Environmental Health recommends ensuring the turnover of any water stored in tanks every 24 hours where possible and movement of water through pipework and outlets at least once a week to prevent it from becoming stagnant. If this is not possible, for example where the building is closed, additional steps are required. In some cases, specialist assistance may be required and this is outlined in the Guidance. The HSE also refers to Guidance available from the European Society of Clinical Microbiology and Infectious Diseases which organisations may find helpful.

Organisations are strongly advised to plan ahead to ensure the risks of legionella are managed and in order to enable organisations to return to work premises, when they are authorised to do so. It should also be noted that where additional steps are required, there may be shortages of supplies to be taken into consideration. For example the availability of certain chemicals, specialist advisors and PPE. As such, planning is essential to avoid delay.

Failure to manage the risks associated with legionella is a breach of health and safety law. Legionnaires disease is a type of pneumonia which can cause serious respiratory illness. The current risks are two-fold: there is an increased risk of legionella bacteria as a result of lockdown but there is also potentially an increased number of people susceptible as a result of a comprised respiratory system caused by Covid-19.