Swiss pools shut down after dangerous Legionella bacteria found in water

A recent investigation has uncovered unsafe bacteria levels in two Swiss public swimming pools. Tests carried out by RTS found excessive Legionella in facilities located in Geneva and Fribourg. The results have raised concerns about water safety in public and private pools across the country.

Seven pools across five cantons—Fribourg, Geneva, Vaud, Valais, and Jura—were examined for Legionella and other harmful bacteria. Among them, Geneva's Bains de Cressy showed 300 Legionella colonies per litre, three times above the legal threshold. Urbanspa in Fribourg also failed tests, recording 500 Legionella colonies per litre and 1,600 colonies of aerobic mesophilic bacteria per millilitre.

The remaining five pools met hygiene standards. Despite the findings, Geneva University Hospitals reported no illness cases linked to their facilities in the last 20 years.

Legionella bacteria grow rapidly in stagnant water heated between 25°C and 45°C. Inhaling contaminated vapour can lead to severe lung infections, particularly in older adults or those with weakened immune systems. Authorities have reminded private hot tub owners to monitor pH and chlorine levels regularly. They also advise hiring certified technicians for system maintenance to prevent bacterial growth.

The investigation highlights the need for stricter water quality controls in public and private pools. While most tested sites complied with regulations, the two failing facilities must now take corrective action. Proper maintenance and expert oversight remain critical to preventing health risks from contaminated water.