The tiny particles that were found are believed to be of watchmakers who use the metals to decorate their expensive timepieces.
Almost $3m (£2.26m) worth of gold and silver end up in the sewers of Switzerland every year.
The study also estimated about 3,000 kg of silver, 1070 kg of gadolinium, 1500 kg of neodymium and 150 kg of ytterbium going to waste, mostly residue from the chemical and medical industries. "The levels of gold or silver were very small, in the micrograms, or even nanograms, but when you add them up it's pretty substantial".
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Overall, however, considering the amounts that could be extracted, the recovery of metals from wastewater or sludge is not said to be worthwhile in a country that refines around 70 percent of the world's gold on average every year. There were also high concentrations in the Ticino area, which is home to gold refineries. This was the only region where it might make sense to recover the metals, Vriens said. Scientists at the Swiss Federal Institute of Aquatic Science and Technology (Eawag) estimated that around 43 kg of gold and 3,000 kg of silver, as well as several other elements end up in wastewater annually.
In September, Swiss investigators launched a probe into why two Spanish women flushed roughly $120,000 down toilets in Geneva.
The Swiss metal concentrations complied with regulations and were removed before humans drank the water again, the study said.
Gold and silver aren't the only valuable items found in Swiss waste water this year.