BBC investigators from the show Watchdog tested 10 samples at numerous chains and tested them for traces of "fecal coliform", which carry several diseases. Fecal bacteria at the Burger Kings and KFCs were at "significant levels".
The coliforms were discovered in three samples of McDonald's drinks, six from Burger King and in seven samples taken at KFC food outlets.
Government guidelines insist such bacteria should never be present in water for human consumption.
It's not as far fetched as you'd think, according to a new investigation of British fast food restaurants by the BBC.
The disturbing findings, which were broadcast on BBC One last night (Wednesday, July 19) come only three weeks after the programme revealed "significant levels" of faecal bacteria in iced drinks in three major coffee chains.
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The findings are worrying, the experts say.
A KFC spokesperson said: "We are shocked and extremely disappointed by these results".
Likewise, Burger King has also stated that "cleanliness and hygiene are a top priority" after the tests. KFC, the worst offender, immediately shut down the ice machines in question in order to conduct its own investigation.
Burger King said it was committed to emphasising standards and training procedures for employees, while McDonald's responded saying it would be "happy to work with relevant industry bodies on ensuring a standard for ice contamination".
So if you're trying avoid ingesting any fecal matter, here's a pro tip: Skip the ice dispenser, fill up on Diet Coke, and enjoy a nice lukewarm soda with your burger. And then you also have to look at hygiene failure with potentially the machines themselves: "are they being kept clean?" said Tony Lewis, head of policy and education at the Chartered Institute of Environmental Health, as quoted by the Liverpool Echo.