Dangerous Legionella levels force two Swiss swimming pools to shut down

A recent investigation has uncovered unsafe levels of Legionella bacteria in two public swimming pools in western Switzerland. Tests carried out in 2025 revealed contamination at facilities in Fribourg and Geneva, leading to immediate closures and disinfection. The findings have raised concerns about water safety in shared swimming spaces.

In early 2025, RTS tested seven public pools across western Switzerland for Legionella contamination. Two facilities failed the checks: Urbanspa in Fribourg and Bains de Cressy in Geneva. The Fribourg pool recorded 500 colonies per litre—far above the legal limit—while Geneva's pool had 300 colonies per litre, three times the permitted amount.

Urbanspa also exceeded limits for aerobic mesophilic bacteria, with 1,600 colonies per millilitre. The facility's director confirmed that four routine tests were conducted in 2025, alongside an unannounced cantonal lab check. The last test, from mid-December, had shown no contamination before RTS's discovery.

Both pools took swift action. Bains de Cressy was closed, disinfected, and later confirmed bacteria-free. Urbanspa replaced all water and carried out thorough disinfection. The remaining five tested pools met hygiene standards.

Legionella bacteria grow in stagnant water between 25°C and 45°C. Despite the findings, Geneva University Hospitals reported no illness cases linked to their facilities in over 20 years.

The incident has highlighted the importance of regular testing and maintenance. Private hot tub owners have been advised to check pH and chlorine levels frequently and seek professional servicing. Public health officials continue to monitor water safety in shared swimming areas.