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Highly magnified image of the bacteria Legionnella, which is responsible for Legionnaires' disease

In July 1976 hundreds of American veterans gathered in Philadelphia, Pennsylvania to celebrate the American Bicentennial.  Within days, these heroes began complaining of muscle pains, fatigue, and chills.

Soon, the disease became fatal.  As the death toll climbed, doctors raced to diagnose the unidentified illness.  Finally, nearly six months later, a cause was determined.  In the Bellevue Stratford Hotel where the veterans had been staying, a pernicious bacterium had been breeding in the cooling tower of the air conditioning system, vented throughout the building, and inhaled by the inhabitants.  The final tally saw 34 deaths among 221 people who required treatment.  The bacterium was named Legionella in reference to the American Legion, a veterans association of which many of the victims were members.

Legionella is a pathogenic (disease-causing) bacterium found in many kinds of water supplies and even the soil.  It is best known as the cause of most cases of Legionnaires’ disease, a pneumonia-like illness that presents with high fever, cough, nausea, and vomiting, among other symptoms.  It can be very deadly, especially for vulnerable demographics such as the elderly.  Standing water kept between 77° and 118°F provides an ideal environment for the growth and development of the bacterium.   Not surprisingly, Legionella thrives in hot tubs, cooling towers in air conditioners, and water heaters. 

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There are several highly effective methods to control Legionella growth or to negate its effects if it has already formed.  The most obvious one is to store cold water below 78°F.  If your water has been sitting at warm room temperature, heating it to 140°F will kill 90% of Legionella within two minutes.  Ultraviolet irradiation is very effective in using ultraviolet light at short wavelengths to kill harmful microorganisms, including Legionella.  City water treatment centers are required to test regularly for Legionella and many other contaminants and generally make liberal use of chlorine and/or chlorine dioxide as a disinfectant.  Unfortunately, chlorine gives water an unsavory flavor and distinct odor, and it won’t be removed by a regular water softener.  If you are experiencing any symptoms of Legionnaires’ disease, contact your doctor immediately.  If you want to eliminate the risk of Legionella from your drinking water entirely, contact your Water Doctors immediately.