Cause of water pollution will remain unclear forever

Drinking water had to be boiled in Zug at the end of September of this year. There are assumptions about the reasons – but there will never be a final certainty.

During a routine check on 30 September 2022, a bacterial contamination was detected in drinking water in the old town of Zug . The WWZ company (Zug Waterworks) had never experienced a similar incident in its history, reported WWZ Energie AG last Friday. In addition, the company writes in its conclusions that the cause "could be limited, but could not be conclusively clarified".

While the focus of the WWZ company had always been on restoring a flawless drinking water supply and on providing customers with clear information, the company also launched an investigation into the cause of the pollution. One possible cause became apparent in the shape of a defective valve in the St. Oswaldsgasse. After extensive flushing work and the replacement of the valve, the corresponding pipe section in the St. Oswaldsgasse was subjected to an inspection with a special camera, whereby no deposits could be detected. "The successful and intensive flushing of the pipes also flushed out any potential traces, however, which makes it impossible to conclusively determine the cause."

The affected water pipes of the WWZ were flushed out from Friday.           Photo: PD
The affected areas in Zug, as of the afternoon of 5 October 2022. Green area declared safe: Blue: areas still affected in the Neustadt area. Purple: affected area in the Vorstadt and Altstadt areas     Screenshot: Website WWZ

The water is again perfect
Measures were taken immediately after the contamination was discovered. By taking water samples systematically, the area was delimited and was immediately separated from the rest of the pipeline network, and the specialists from the WWZ flushed out all drinking water pipes in the corresponding area. "Thanks to these comprehensive measures, for which at times more than 30 employees were deployed at the same time, the WWZ was able to fully ensure the usual high quality of drinking water in the city of Zug within ten days."

Since then, the samples have been taken closely, confirming the "impeccable quality". In total, around 250 samples have been taken since 30 September 2022. In order to be able to guarantee the high quality of drinking water at all times, a systematically increased number of samples will continue to be carried out in consultation with the Office for Consumer Protection.