Legionella is a bacterium commonly associated with Legionnaires’ disease. Legionnaires’ disease is a type of pneumonia. It was named after an outbreak of severe pneumonia that affected a meeting of the American Legion in 1976.

Legionellosis is the name given for a group of illnesses associated with legionella bacteria. There are three main illnesses caused by the bacteria
1) Legionnaires’ disease
2) Pontiac Fever
3) Lochgoilhead Fever.

Normally it is contracted by means of the bacteria being aerosolised and then inhaled. High susceptible individuals may get infected at relatively low doses

The Health and Safety at Work act 1974 and the Control of Substances Hazardous to Health Regulations place legal duties on employers and those responsible for the control of premises to control the risk from exposure to bacteria.

The Approved code of Practice and guidance more commonly known as L8 gives advice on these legal duties and sets out strategies for controlling the risk.

The five key areas that are required to comply with legal duties are;

>Identify and assess source of risk
>Prepare a scheme for preventing or controlling the risk
>Implement, manage, and monitor precautions
>Keep records
>Appoint a person to be managerially responsible

There are several measures that can be adopted to create water systems in the built environment that are hostile to the growth of legionella. Most traditionally, temperature is used to control legionella. Wherever possible, temperature should be the first line of defence used to control the bacterial growth.

System Required Temperature:

Hot water storage - 60 Deg. C
Hot Water Distribution Greater than - 50 Deg. C
Cold water Storage Less than - 20 Deg. C
Cold Water Distribution Less than - 20 Deg. C

It is also particularly important to ensure that all areas of the distribution system are in regular use to safe guard against stagnation.

The control scheme which will be completed and detailed in the legionella risk assessment report will identify the tasks that are required to control the risks. The level of monitoring required will depend on the type of water systems and services and users within your site. A basic water system for example in a 5-storey office block may require monthly temperature checks, six monthly & annual inspections (other tasks may include quarterly shower head cleaning or weekly flushing of infrequently used outlets).

Specific guidance regarding the control of legionella bacteria is supplied in Legionnaires’ disease – The control of legionella bacteria in water systems. Approved Code of Practice and guidance L8.

Downloadable from the HSE website – www.hse.gov.uk/pubns/priced/l8.pdf

A leaflet briefly defining your legionella obligations is downloadable from the HSE website and we strongly recommend you take the time to read this leaflet as a starting point Legionnaires’ disease a guide for employers – Click Here