Legionella/WBP bacteria colonize (grow) within biofilms located inside water distribution system piping particularly warm water systems. Recolonization of Legionella/WBP is very likely to occur after an initial short term water disinfection treatment. Once a water distribution system is colonized with Legionella, the water system remains at risk for Legionella growth. In 1982, Legionella was found to be ubiquitous in the hot water distribution of a VA hospital experiencing an on-going outbreak of Legionnaires' disease.



Legionnaire's disease is a form of pneumonia linked to the Legionella bacteria - a water borne pathogen (WBP). The correct diagnosis of Legionnaires' disease requires specialized tests to distinguish it from other forms of pneumonia and as a result it is easily overlooked.


Bacteria Colonize

At risk?


Reducing the risk

Legionnaires' disease was first identified and named in 1976 when a group of American Legion Convention attendees became ill from what was later traced to a cooling tower colonized with Legionella. The exposure resulted in multiple illnesses and fatalities. Subsequent studies indicate that at risk populations include: the elderly, cigarette smokers, diabetics, cancer patients, cancer survivors, those with chronic lung issues, those recovering from surgery, bone marrow and solid organ transplant patients and HIV patients.


People in certain occupations, such as those who do maintenance work on large air-conditioning systems, may also be at increased risk of exposure to Legionella bacteria.

Generally, more men than women contract Legionnaires’ disease. It is uncommon for people younger than 20 years of age to get Legionnaires’ disease



In addition to pneumonia, symptoms can include fever, cough, muscle pain and headache. Symptoms start within 2 to 14 days of infection, and can last for several months.


If symptoms persist, consult your health care provider. Most cases can be treated successfully with antibiotics. Effectiveness of the treatment varies with age and overall health, and can also depend on how quickly the person receives the right medical treatment.

The risk of getting Legionnaires’ disease is generally quite low.


In your home, you can reduce the risks through proper maintenance of all mist-producing devices, such as shower heads, hot tubs, whirlpool bathtubs, and humidifiers. Make sure you clean and disinfect these devices regularly according to manufacturer directions. Keeping your home water heater at a suitable temperature (a minimum of 60°C) will also help prevent the growth of Legionella. However, to reduce the risk of scalding, it is important that temperature of the water be no higher than 49°C at the tap. A qualified plumber should be contacted to install mixing valves to control the tap water temperature.


20 c

Certain conditions that may be present in buildings and homes promote the growth of the bacteria. These include stagnant water, warm water temperatures (especially between 20°C and 50°C) and the presence of biofilm, scale and sediment. These conditions may be found in:


cooling towers, such as those used with the air conditioning systems of large buildings;

whirlpool bathtubs, hot tubs and public spas;

plumbing systems (including water heaters, faucets and showers) either in the home or in larger buildings; and



Legionella bacteria are found in natural water sources such as lakes, rivers, ponds, and streams generally at levels that are too low to cause disease in people. Cases of Legionnaires’ disease have occurred in many different settings, including homes, commercial buildings, spas, cruise ships and health care facilities. Legionnaires’ disease cannot be spread from one person to another. The number of bacteria determines the risk for humans.


The following people are at greater risk of developing the disease:


individuals over 40 years of age;



people with chronic lung or kidney disease;

people with diabetes; and

people with weakened immune systems due to conditions such as cancer or an organ transplant.


How you get it?

Canadian Invironmental Services provides  complete detection services for legionella.  Our team has encountered many situations where possible cases of legionella contamination existed.


contact our offices today to find out how we can help you determine and rule out the possibility of legionella in your building.







10485 keele st.

Toronto, Ontario

N2G 3M7

Toll Free: 1 (888) 388 MOLD





626 Cataraqui Woods Drive,

Suite 11, Kingston, Ontario

K7P 1T8

Toll Free: 1 (888) 388 MOLD



Bradford-Orillia North

118 Lee Avenue

Bradford, Ontario

L3Z 1A9

Phone: (905) 716 2275

Fax: (905) 775 5078

Toll Free: 1 (888) 388 MOLD

Email: iaq@invironmental.ca



207 Madison Avenue South, Unit #2

Kitchener, Ontario

N2G 3M7

Toll Free: 1 (888) 388 MOLD




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