Prevention of Legionnaires' Disease Committee's recommendations arising from finding of Legionella bacteria at Tamar

The following is issued on behalf of the Prevention of Legionnaires' Disease Committee:

The Prevention of Legionnaires' Disease Committee met today (February 8) and made recommendations on issues arising from investigation of the recent detection of Legionella bacteria at the Tamar Central Government Offices and Legislative Council Complex.

The meeting noted the investigation findings and follow-up actions taken by the various government departments at Tamar, informed by discussion with Professor Yuen Kwok-yung of the Department of Microbiology at the University of Hong Kong. The Committee noted that the presence of Legionella bacteria in the cold/hot water systems is inevitable due to the ubiquitous nature of the organism in aqueous environments. It endorsed the view that stagnation of water in warm temperature at affected sites in Tamar might have led to the proliferation of Legionella bacteria, and noted that such proliferation had been effectively reduced to acceptable levels after thorough disinfection, and noted that remedial actions had been taken.

After reviewing international guidelines, including the guidelines of the World Health Organization (WHO) and the United Kingdom's Health and Safety Executive, and considering experts' opinions and advice, the Committee was of the view that regular testing for Legionella bacteria in cold/hot water systems in buildings in the community is generally not required. The WHO holds the view that the most important factors concerning control of Legionella proliferation are appropriate design, control of risk factors and maintenance of individual systems. Testing for Legionella should be conducted for investigation upon notification of a human case of Legionnaires' Disease in the buildings concerned.

The Committee also confirmed that testing of Legionella bacteria in cold/hot water systems of newly completed buildings is not necessary. The Committee recommended that new cold/hot water systems including water tank and distribution pipes should continue to follow the Water Supplies Department (WSD)'s current guidelines on cleansing and disinfection upon completion, which is in line with the WHO's recommendations. Details of the WSD's guidelines are available at the following links: and .

The Committee discussed the need to review the existing Code of Practice (CoP) for Prevention of Legionnaires' Disease issued to promote public awareness of the disease and provide technical guidelines on prevention measures. In light of the findings of the Tamar case, the CoP would be reviewed regarding the design, operation and maintenance precautions of cold/hot water systems as appropriate, particularly in respect of the flushing of infrequently used water pipes/outlets and localised water heaters with reference to international guidelines. The CoP is available at the following link: .

Public education is also considered an important part of increasing public awareness on prevention of Legionnaires' Disease, and new initiatives would be taken.

The Committee was set up in 1985 to advise the Government from the public health, microbiology and engineering services perspectives on the minimisation of the risk of Legionnaires' Disease, and the promotion of good practices to building owners and associated practitioners to prevent the outbreak of Legionnaires' Disease.

The Committee is currently chaired by Professor Sian Griffiths, and is composed of five non-official members from academia and industry stakeholders and seven official members from the Government.

Ends/Wednesday, February 8, 2012
Issued at HKT 19:28