Legionnaires' Disease: The control of Legionella bacteria in water systems (L8) 2001, is a combined Legionella Approved Code of Practice and Guidance document which provides clearly defined requirements for the control of Legionella within all water systems. In addition, there are additional pieces of legislation that can be applied, including:

• Health and Safety at Work Act 1974
• The Management of Health and Safety at Work Regulations 1999
• Control of Substances Hazardous to Health Regulations 2002 (as amended)
• Water Supply (Water Fittings) Regulations 1999
• Water Systems Health Technical Memorandum 04-01: The control of Legionella
• Hygiene, “safe” hot water, cold water and drinking water systems

The initial requirement is to undertake a Legionella Risk Assessment of the premises. This will identify and assess the risk of exposure to Legionella bacteria from work activities and water systems on the premises. Once a risk system has been identified it will be necessary to determine whether the risk of exposure can be prevented, or if prevention is not reasonably practicable, the means by which exposure is to be controlled.

Where the risk of exposure cannot be prevented, for example by removal of the risk system, then it must be controlled through routine monitoring and inspections. This is referred to as the written scheme.

The written scheme will be tailored to control the identified risk and will vary according to the type of water system. It is vitally important that the results of the written scheme are recorded, as this will provide documentary evidence to support that the Legionella risk is being controlled. This is normally recorded in the water system logbook, which should be frequently audited to confirm satisfactory completion.

Finally, the risk assessment needs to be reviewed at least every two years. This may be sooner if; there is a suspected outbreak of Legionnaires’ disease, the results of checks indicate that control measures are no longer effective, changes to the use of the building or changes to the water system.