More than a quarter of ice cubes used in Swiss bars and restaurants contain fecal bacteria such as E. coli, according to a nationwide study by the Swiss cantonal chemists association (VKCS).

In an analysis of ice cube samples collected from bars, restaurants and canteens around Switzerland last year, 26 percent fell short of legal health standards, said Sunday paper SonntagsBlick, which released the figure prior to the report’s official publication.

The presence of bacteria including pseudomonas, E. coli and enterococci is “a clear sign of unsanitary production of ice cubes,” Otmar Deflorin, president of the  cantonal chemists association and head of the Swiss federal laboratory in Bern, told SonntagsBlick.

The primary cause is a lack of hygiene in bars and restaurants, where ice machines may be badly cleaned and maintained, he said.