(BUSINESS INSIDER) -- It's hard to match the refreshing taste of an iced coffee on a hot summer day — but a new BBC investigation may make you think twice before you order a chilled drink.

The BBC's consumer-affairs "Watchdog" program found that samples of iced drinks from Starbucks and two other UK chains — Costa Coffee and Caffe Nero — contained "varying levels of the bacteria."

Along with the ice, researchers also studied the cleanliness of tables, trays, and high chairs at 30 of the coffee-chain branches.

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