Legionnaires’ Disease and Your Household Water

Legionnaires’ Disease and Your Household Water: What You Need to Know


What is Legionnaires’ disease? 


Legionnaires’ disease, a severe form of pneumonia, is caused by breathing in droplets of water containing Legionella. Symptoms usually occur within two weeks following exposure and include:


• Cough

• Shortness of breath

• Fever

• Muscle aches

• Headaches


Who is at increased risk?


In most cases, healthy people exposed to Legionella do not get sick. The following people are at an increased risk of getting sick:


• People 50 years or older (especially current or former smokers)


• People with a chronic lung disease


• People with weak immune systems


• People with underlying
 illnesses such as diabetes, cancer, or kidney failure


What should I do if I think I have Legionnaires’ disease? 


If you develop symptoms and may have been exposed to Legionella, see a doctor right away. Legionnaires’ disease is treated with antibiotics (drugs that kill bacteria in the body). Most people who get sick need care in a hospital but make a
 full recovery.


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.


Where does Legionella grow and spread? 


Legionella can grow in many parts of a water system that are continually wet, and certain devices can then spread droplets of water containing the bacteria. Examples of areas where Legionella can grow and spread include: water storage tanks, water filters, faucets, aerators, showerheads, hoses, pipes, hot tubs, and humidifiers.


Home air-conditioning units are not at risk for Legionella growth because they do not use water to cool the air.


What factors or conditions can lead to the growth or spread of Legionella in my household water? 


• Temperature of hot water tank is set too low


• Infrequently used showers or sinks


• Build-up of sediment (dirt) in hot water tank


• Not following manufacturer’s instructions for maintenance and replacement of water filters and other devices


Best Practices for Preventing the Growth of Legionella 


• Let your faucets and showers run for at least three minutes when they have been out of use for more than a week. 


• Thoroughly clean or replace your shower heads and faucet aerators (screens) 3-4 times per year. 


• Drain and flush your hot water tank every 6-12 months. Consider hiring a licensed plumbing professional to perform this procedure. 


• Clean and/or replace all water filters per manufacturer’s instructions, such as whole house (e.g., water softeners) and point-of-use filters (e.g., built-in refrigerator filters). 


Remove, shorten, and/or regularly flush existing dead legs (a section of pipe with low use).


For future renovations, ensure your plumber avoids creating dead legs.


• Avoid high-risk activities. If you are at an increased risk for Legionnaires’ disease, consider avoiding power washing, or similar activities, which may generate increased amounts of aerosols or mist.


• Medical devices and portable humidifiers should be operated, cleaned, and disinfected per manufacturer's instructions. Do not use tap water if sterile water is required.


• Keep your hot water tank set to a minimum of 120° F. This temperature will reduce Legionella growth and minimize risk of hot water burns. Although setting the tank up to 140° F is best for controlling Legionella, especially if at-risk individuals are in your home, if the temperature is set to greater than 120° F a mixing valve must be installed to prevent hot water burns when using the water. Be sure to check with manufacturer recommendations prior to raising the temperature.


• Drain garden hoses and shut off the water line when not in use for the season. 


• Maintain chemical levels in your hot tub per manufacturer’s recommendations.


Other Resources


New Jersey Department of Health Legionellosis (Legionnaires’ Disease and Pontiac Fever) Web Page



New Jersey Department of Health FAQ Sheet



CDC Resource: Toolkit for Controlling Legionella in Common Sources of Exposure



Maintaining and Reopening Building Water Systems Impacted by Prolonged Shutdown or Reduced Operation: Minimizing Legionella and Opportunistic Bacteria Growth