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Resuming Safe Operation of Building Water Systems

Information for Building Maintenance Superintendents, Engineers, Managers, and Other Personnel

As building managers in areas affected by disasters attempt to restart clean water systems, care should be taken to reduce the risk of legionellosis, also known as Legionnaires' disease. Legionnaires' disease is a form of pneumonia that is acquired from aerosolized water containing the bacteria Legionella. Legionnaires' disease can be very serious, causing death in up to 30% of cases, usually in older people or those with weakened immune systems. Growth of Legionella is enhanced in warm, stagnant water; plumbing systems that have been out of use for any reason, including a disaster, provide such an environment. Transmission to humans requires aerosolization by shower heads, cooling towers, whirlpool spas, or other similar systems.

To help minimize the risk of Legionnaires' disease, the Centers for Disease Control and Prevention (CDC) has partnered with the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE®), a not-for-profit organization that develops standards and guidelines for industries that design, manufacture, and maintain building systems. With substantial input from CDC and industry experts, ASHRAE developed "ASHRAE Guideline 12-2000 – Minimizing the Risk of Legionellosis Associated With Building Water Systems". The guidelines provide specific environmental and operational guidelines that will contribute to the safe operation of building water systems.

For more information, visit Resuming safe operation of building water systems—risk of Legionnaires' disease.

To learn more about legionellosis, visit CDC’s Legionellosis Website.

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