Legionellosis is a potentially fatal disease caused by a bacterium, Legionella, which is quite common in nature. It is found in small quantities in most surface waters. It thrives best in warm stagnant water (± 40°C). It cannot survive temperatures above 60°C and dies relatively quickly.
The disease is caused by inhaling airborne microdroplets containing Legionella bacteria. In contrast, there is no real risk when ingesting contaminated water.
The inhalation hazard comes mainly from showers, hot tubs and air conditioning systems in large buildings (hotels, schools, sports centres, hospitals). Cooling towers in buildings and industry are another major source of danger. The risks are increased in hospitals and nursing homes, as these are the places where people are least resistant to the disease.
In order to limit the presence of Legionella in local authority buildings as much as possible, preventive action is of the essence.
If your indoor pipes are insulated, you can maintain a constant temperature above 50°C in the circuit, thereby preventing the growth of the bacteria.
The Scientific and Technical Centre for Construction (BBRI) provides practical recommendations and advice for large buildings subject to specific legal requirements.
At your request, our laboratory can carry out sampling and analysis of Legionella in domestic hot water systems under ISO 17025 accreditation. Depending on the origin of the tap water, the enumeration of bacteria by culture may be preceded by qualitative detection of negative samples (absence of Legionella pneumophila) by gene amplification (PCR). Results are available within 24 hours. In this case, the culture analysis is then started only in the presence of PCR-detected Legionella DNA.
If your request concerns Legionella analyses on cooling tower water, we subcontract these to an external ISO 17025 accredited laboratory.
The risk of catching Legionnaires' disease is not usually a problem in individual dwellings. However, there are some precautionary measures you can take:
Tap water must meet a large number of quality parameters. These are set by the standards of the Walloon Water Code. The water from our network is analysed daily to ensure that it complies with the standards.
Water quality must meet the legal standards applicable to drinking water. This quality is strictly controlled, but a problem cannot be ruled out completely.
If in doubt, contact us. We will always look into your query carefully.If necessary, we will send a technician on site for further investigation. They may take water samples. The laboratory analysis will determine any corrective measures to be taken to bring the situation into compliance.
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