AUGUSTA – The Maine Center for Disease Control and Prevention (CDC) announced last Wednesday (Aug. 14) that recent water tests in the Orono-Veazie Water District did not detect Legionella bacteria.

Maine CDC has worked in close coordination with the Water District to boost chlorine levels throughout the system in response to finding Legionella bacteria at two locations in July. While lower bacteria levels are ideal, the water was safe to drink before and throughout this testing. Maine CDC said it appreciatds the Orono-Veazie Water District’s quick response to reduce levels of the bacteria.

Maine CDC worked with the Water District to conduct the testing as part of the investigation into a cluster of six cases of Legionnaires’ disease in the Bangor area since November 2018. Maine CDC has not linked the previously detected Legionella bacteria in the Water District to these six cases, which could be coincidental with no common exposure. Legionnaires’ disease is a type of pneumonia that may result from breathing in droplets of water that contain Legionella bacteria.

No additional cases of Legionnaires’ disease have been identified since the July 12 announcement of this investigation. Maine CDC continues to monitor for any new cases.

There were almost 7,500 cases of Legionnaires’ disease in the United States in 2017. Last year, there were 33 cases of Legionnaires’ disease in Maine. Because it is underdiagnosed, these numbers may underestimate the true incidence.

Legionella is a type of bacteria found naturally in freshwater environments, like lakes and streams. It can become a health concern when it grows and spreads in human-made building water systems like sinks, cooling towers, hot tubs, fountains, and large plumbing systems. Most healthy people exposed to Legionellado not get sick. Those at increased risk of getting sick are people aged 50 years and older; current or former smokers; people with a chronic lung disease, weak immune systems, or cancer; and people with other underlying illnesses such as diabetes, kidney failure, or liver failure.


Legionella is much less likely to contaminate the water in houses than in large buildings with complex water systems. However, homeowners can take steps to reduce the risk further, including:

Water Heaters: In some cases, bacteria have been found in residential water heaters, more often in electric water heaters than in gas water heaters. Most manufacturers recommend that water heaters be flushed on an annual basis, which can help reduce the risk of bacteria growth. This should be done with caution and performed by a qualified plumber.

Showers: Because they remain damp, shower heads can grow bacteria. Removing the shower head, manually cleaning it to remove scale and sediment, and soaking it in a mixture of 1 tablespoon of household bleach to 1 gallon of water for about 2 hours will disinfect the shower head.

Humidifiers: Some homes have whole-house humidifiers. Humidifiers should be cleaned and disinfected regularly according to the manufacturer’s directions. Always unplug the humidifier first. Clean the inside of the humidifier per the manufacturer’s instructions, using a mixture such as 1 tablespoon of household bleach to 1 gallon of water, and dry.

CPAP Machines and Nebulizers: These devices should be used only with distilled water and should be cleaned regularly, per manufacturer’s recommendations.

For more information on Legionella visit: Maine CDC’s webpage at, or the Federal CDC’s webpage at

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