No Legionella risk

Today’s edition of Tages-Anzeiger includes an unspecific report claiming the suspected presence of Legionella at the Hönggerberg campus. The fact is that the only part of the campus affected was the HPL building. The building has now been given the all clear. The problem was dealt with immediately and, as a result, the emergency precautionary measures put in place have now been lifted.

Enlarged view: HPL ETH Hönggerberg
Legionella contamination was suspected in the HPL building at ETH Zurich in Hönggerberg. (Image: Michael Sieber, Langnau/Zurich)

During laboratory tests of the hot water at the ETH campus in Hönggerberg, elevated concentrations of Legionella were detected on Tuesday 8 April and on Thursday 10 April. The levels exceeded the tolerance limit for high-level contamination set by the Swiss Federal Health Ministry (10,000 germs per litre). As an immediate measure, all the showers in the HPL building were closed and users were told to refrain from using hot water in the laboratories, washrooms, kitchens, etc. An email was sent out immediately to all employees in the building to inform them about the suspected contamination. In order to rectify the problem as quickly as possible, the tap water was heated to more than 60 degrees and the pipes were flushed, leading to a rapid reduction in Legionella.

Further tests were conducted on 11 April. The levels recorded in these tests were substantially below the tolerance limit, which means that there is no longer a Legionella risk. As a result, all immediate measures were lifted during the course of Monday afternoon. The hot water in the HPL building is now safe to use again.

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