U bent hier: Home » Your health and safety » Legionella


Legionella is a bacterial species that in certain circumstances may cause a contamination of drinking water. WEB does everything in its power to prevent legionella contamination. There are also measures you should take care of yourself. Legionella is a matter that concerns us all.

What is legionella?

Legionella naturally appears wherever it is moist, in soil and in water. Legionella bacteria are as inevitable as all other types of bacteria. This means that also on Bonaire legionella is present in drinking water. The numbers are so small that the bacteria pose no threat.

In stagnant water legionella bacteria grow and reproduce very rapidly. This occurs if there is a bio film – a thin layer of micro organisms that is deposited on surfaces that are in contact with the water – and at temperatures between 25 to 45 degrees Celsius (77 to 113 degrees Fahrenheit). There are 14 types of legionella bacteria, all of which appear in drinking water.

What is Legionnaires’ disease?

Legionnaires’ disease is pneumonia caused by legionella bacteria. The disease should be treated with antibiotics as soon as possible. The name is derived from the first recognized outbreak in 1976 in the USA, amongst army veterans. There is also a milder form, legionella flu or Pontiac fever. This infection develops like a ‘normal’ flu and can clear up without treatment.

How do people get infected?

Infection occurs by inhalation of very small droplets of contaminated water (mist of aerosol). Think of a shower, hot tub, steam bath or a fountain. Legionella enters the respiratory tract through inhaled aerosols and can then cause an infection. People do not get sick from drinking contaminated water. Also, legionella is not transferable from person to person, meaning that it is not contagious.

Who are most at risk of getting sick?

The majority of people who get infected with legionella do not develop Legionnaires’ disease. Groups at increased risk of getting the disease are people from middle age, smokers, heavy drinkers and people with low resistance due to illness or old age.

What is the course of the disease?

The time between infection and becoming ill is between 2 and 18 days. Symptoms include headache, muscle pain, fatigue, high fever, coughing and shortness of breath. Pontiac fever usually passes on its own.

What should I do to prevent legionella contamination?

There is no vaccination against Legionnaires’ disease. Note the following to reduce the risk of legionella:

  • Most important is that water in pipes and drains in buildings and gardens does not stagnate too long. Rule of thumb: no longer than 7 days.
  • Flush pipes and drains well if they have not been used longer than 7 days.
  • Make sure all taps, showers, toilets and any sprinkler systems are regularly used.
  • Clean hot tub, jacuzzi or humidifiers well according to the instructions.
  • Set water heaters properly: minimum at 60 degrees Celsius (140 degrees Fahrenheit).
  • Is there anyone using an apnea device? Note that the water reservoir has to be filled with cooled boiled water that is refreshed daily. The mask should be cleaned daily. The tank must be cleaned and disinfected weekly.
  • Decalcify showers regularly.
  • Let garden hoses drain well after use.
  • Be alert: if the water has a strange smell, an aberrant color or is cloudy, something could be wrong.

Do you suspect contamination?

Call the emergency service number of WEB: telephone 9215, 24 hours a day, 7 days a week.

What does WEB do?

  • Half-yearly survey
    WEB is legally obliged to inspect the drinking water every six month on legionella. Following a fixed program we take samples of the entire production and distribution network, including the reservoirs. The water samples are subjected to bacteriological and chemical analyses. If we determine any exceeding of the norm, the pipe will be flushed and, if necessary, disinfected. If there is an intermediate suspicion of contamination, the water is promptly investigated.
  • Notification and information obligation
    WEB is legally obliged to report a legionella contamination to the Human Environment and Transport Inspectorate (ILT) Dutch Caribbean, and to the people who might be affected. WEB must also inform society and raise awareness of legionella and how to reduce the risk of contamination.
  • Prevention
    WEB takes prevention seriously and is eager to inform its clients by means of this brochure and other media. Information about legionella – and above all: the prevention of legionella contamination is also distributed via our website, our Facebook page and radio and television spots. Also prevention is a matter that concerns us all!

Information for companies and institutions

Most companies and institutions have a collective drinking water installation that is used by all kinds of people. The owner of a building is responsible for the quality of the water, from the meter to the water taps. The owner has a legal duty of care, implying that the water users’ health should not be jeopardized.

Since July 1, 2016, the regulations for drinking water have been updated. Under the new rules, the owners of drinking water installations must have a legionella risk assessment and management plan. WEB must half-yearly perform a sampling of legionella in the water supply network. If legionella is detected above the standard of 100 colony-forming units per liter (100 cfu/l), WEB takes action. If the standard of 1000 cfu/l is exceeded, WEB will inform its clients in the relevant area as well as the supervisor, Human Environment and Transport Inspectorate (ILT) Dutch Caribbean.

The new regulations no longer require companies and institutions to have samples taken and analyzed on legionella. However, the owner of the water installation remains responsible for the quality of the drinking water. Hence, WEB recommends companies and institutions to perform a risk assessment on their network and half-yearly have samples analyzed on legionella.