Duty of Care – Legionnaires’ Disease

Legionnaires’ disease is a potentially fatal form of pneumonia caused by breathing in small droplets of contaminated water containing Legionella. All man-made hot and cold water systems are likely to provide an environment where Legionella can grow. Where conditions are favourable (i.e. suitable growth temperature range – in a domestic setting, it can multiply where there is water stored between 20°C and 45°C; water droplets (aerosols) produced and dispersed; water stored and/or recirculated; some ‘food’ for the organism to grow such as rust, sludge, scale, biofilm etc) then the bacteria may multiply thus increasing the risk of exposure.  It is a simple fact that the organism will colonise both large and small systems so both require risks to be managed effectively.

Duty of care
Landlords have a duty of care to the tenants they house, and as such have to be aware of potential dangers to tenant health. These range from the visible like the integrity of the structure or ensuring the electrics are safe, to the less obvious and potentially hidden dangers like Legionnaires’ Disease.

Although the legionella organisms are more likely to appear in large systems such as cooling towers, air conditioning systems and whirlpool spas… Legionella bacteria can also multiply in the water systems and storage tanks in residential properties.

Showers, boilers and other smaller tanks may still support the growth and proliferation of legionella organisms. In multi-occupied buildings, there is often inadequate pressure from mains water to supply all dwellings, so water may be stored. This could be in a header tank at the top of the block or even tanks at a lower level, with booster pumps to supply water to the units. Any such tank presents potential places for the bacteria to grow.

It is estimated that up to 1.5 million houses could be contaminated with the legionella organism, with 532 confirmed cases reported in England and Wales in 2018. To reduce risk to tenants, landlords should look at their entire water system to identify potential sources of contamination or exposure.

Landlords have a legal responsibility to prevent tenants contracting Legionnaires’ Disease.

Health and Safety legislation encourages landlords to carry out risk assessments and thereafter maintain control measures to minimise the risk. Most rented premises will be relatively low risk but it is important that risk assessments are carried out and control measures introduced, to prevent serious legal repercussions on the Landlord and possible criminal conviction.

Risk Assessment
In most residential properties where smaller domestic water systems are installed and there is regular water usage, a simple assessment should be carried out and where this shows the risks are low, no further action is required. The risk is even lower where combi-boilers are installed and hot water is instantaneous, as there is no water storage but simple control measures will ensure the risks remain low.

If any risks are identified there must be action to prevent or control them.


For more information visit the Health and Safety Executive on Landlords’ responsibilities.