Legionnaires' Disease and Cooling Tower Water: Truths Behind the Safety Concerns

Garratt-Callahan Companyapproximately 25 thousand Americans suffer from the flu-like symptoms caused by Legionnaires' Disease (LD), a water-borne bacterial infection. Legionnaires' Disease, also known as Legionellosis, has been the subject of recent publicity due to an established association between it and cooling tower waters.

The Legionella bacterium is extremely common in the environment. It can be found in lakes, rivers, spas, showerheads, and many standing waters including cooling towers. In a cooling tower, aerosols (mist-like droplets of water) are formed and transported into the environment through the tower exhaust. If Legionella bacteria are present in the tower water, breathing the aerosols can result in the contraction of Legionnaires' Disease.

As with most diseases, the mere presence of the bacteria does not necessarily constitute a threat. Catching LD requires a susceptible person, the right environment, a virulent strain of the organism, and a high enough dose of the bacteria entering the body via an infectious route. Proper cooling tower maintenance can reduce the possibility of hazardous levels of the bacterium developing in a tower.

The United States Centers for Disease Control has acknowledged that the Legionella bacterium is so common in the environment that there is simply no way to eradicate it. They do not recommend routine testing of cooling towers due to the expense, difficulty, inaccuracy, and unreliability of the tests. The U.S. Environmental Protection Agency will not allow any claims that biocides can control the bacterium.

How Can a Cooling Tower Operator Keep the Water Safe?
Fortunately, the means to reduce the possibility of the Legionella bacteria developing in cooling tower waters is readily available and is easy to implement. Because bacteria are less likely to flourish in a clean system, normal cooling tower maintenance will reduce the possibility of an outbreak of LD occurring in a building.

"We work hard to keep on top of state and Federal guidelines concerning LD. They all stress that complete control is unlikely, but that adhering to a proper treatment program is the key to risk reduction," said William Dignin, chief microbiologist with Garratt-Callahan Company.

The Centers for Disease Control and most State and City Health Departments recommend the following procedures in order to reduce the risk of harboring hazardous levels of Legionella bacteria in cooling towers:

• Keep the tower clean of dirt and other environmental debris via routine manual cleaning.
• Regularly scheduled use of biocides will help to control and interior growths.
• Use effective inhibitors to control corrosion and scale in the system.

By simply adhering to a proper cooling tower treatment program, the operator can ensure the health and safety of the water.

Edited by Tracy Fabre from information provided by <%=company%>, CA