What is Legionella, and what should I know about Legionella in my well water?

Legionella is a type of bacteria that can cause a mild case of the flu called Pontiac fever, or in severe cases, pneumonia or Legionnaires’ disease can occur and are sometimes fatal. Named after a 1977 outbreak at an American Legion conference, Legionella is found naturally in water. It can multiply in heating systems, including hot water tanks, and can pose a risk to humans.

Legionella can live in the biofilm that accumulates in your water system. This biofilm can break free carrying the bacteria to areas at the end of your water lines, such as a shower head. The bacteria can then become aerosolized where a person may breathe it in. According to the CDC’s Legionella webpage, the most vulnerable risk groups include older individuals, current or former smokers, and those with pre-existing health conditions.

Most Legionella cases are community-acquired, specifically with origins in cooling towers, hotels, and hot tubs. However, there is little research about the role of private well systems in outbreaks of Legionnaires’ disease. Researchers are still working to figure out how Legionella can grow and impact private well systems.

If someone who uses your well water is diagnosed with Legionnaires’ disease or Pontiac fever, contact your local health department or a certified laboratory and discuss testing options.

While there is not a specific treatment to prevent Legionella in private well systems, there are important factors to consider monitoring that can cause increased Legionella growth. This includes sediment levels, biofilm accumulation, disinfectant residual, water age and temperature. Visit the CDC's Controlling Legionella in Potable Water Systems for the most up-to-date information, or contact a water treatment professional - we would recommend contacting a water treatment professional who has been certified through the Water Quality Association’s Professional Certification Program.

If you are concerned about Legionella, speak with your doctor or local health department for more information. You can also contact us through the chat feature or call us at 866-945-0699.