Why student residences should be particularly vigilant against Legionnaires' disease this summer
- Jonatan De Winne
- Dec 10, 2025
- 3 min read
"Nothing is as invisible and invasive as a bacterium quietly hiding in your showerhead."
1. What is Legionnaires' disease and why should you take it seriously?
Legionella pneumophila is a bacterium found in tap water. Inhaling nebulized water (aerosols) can cause severe pneumonia (Legionnaires' disease) or severe influenza (Pontiac fever). Without treatment, the mortality rate of Legionnaires' disease can reach 10 to 15%. Smokers, the elderly, and immunocompromised individuals are particularly vulnerable. However, the long-term effects of COVID-19 are still unknown, meaning the at-risk group is potentially larger than previously thought. The infection is not transmitted through drinking water, but through the inhalation of aerosols, for example, in the shower.
2. Student accommodation: a perfect storm in July and August
Stagnant water – during the summer holidays, shower hoses remain unused for weeks; biofilm and sediment provide places for growth.
Hot pipes – in an attic or poorly ventilated technical duct, the cold water network easily exceeds 25°C in July — an ideal breeding ground for Legionella.
The September back-to-school wave : when hundreds of students return at once and shower en masse, the accumulated bacterial load is released all at once. Laboratories experience a peak in infections every year at the end of summer.
3. The legal aspect: the Legionella decree also applies to student accommodation.
Flanders classifies places where "children, young people, or students are received, housed, or cared for" as establishments accessible to the public (Legionella Decree, Art. 1, definition 28°d). Depending on the number of rooms in the building, these establishments fall into the category of moderate-risk establishments with a communal hot water supply. In addition to the family's obligation to provide drinking water, this also entails specific obligations:
Obligation | Explained briefly |
Legionella Management Plan | Inventory, risk analysis and preventive measures for all taps. |
Temperature control | Hot water min. 60 °C (supply) and 55 °C return; cold water < 25 °C. |
Rinsing and measurement protocol | Regular rinsing and monitoring based on sampling and analysis |
In short: if you rent student rooms with showers inside the building, you are required, for health and legal reasons, to ensure that these showers are protected against Legionella. Although the legislation depends on the size of the building, we recommend that you begin taking Legionella prevention measures in all cases. The temperature measurements below, taken in different types of buildings, are unfortunately the rule rather than the exception in summer:
Cold water | Hot water |
 |  |
 |  |
 |  |
4. Practical checklist before the hangars fill up again
Rinse all taps – run hot and cold water until the temperature is stable.
Set the boiler to 60°C – and check after 24 hours if a value of 55°C is actually reached at the tap.
If in doubt, perform a thermal shock : increase the temperature to 70°C and rinse all pipes, shower heads and mixer taps.
Clean and descale shower heads and aerators; limescale and biofilm are a breeding ground.
Document everything in the management plan: date, time, temperature, rinsing time, any corrections.
Inform the students : display an A4 document with simple instructions or send an information sheet ("First shower? Rinse for 2 min.").
5. Conclusion: Don't let bacteria be your first guest
A student room is a veritable breeding ground for ideas and ambitions – don't let it become a breeding ground for Legionnaires' disease. With a well-thought-out management plan, concrete measures, and clear communication, you can create a solid safety barrier between your students and this invisible pathogen.
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