Some studies and news stories over the past decade lend credibility to these bartenders’ warning about ice machines. In 2014, HuffPost spoke to two experts on ice and ice machine contamination. Three main issues were discussed in the piece: mold, bacteria, and whatever is found on people’s’ hands.
These contaminants can come from a variety of places. Mold can build up in ice machines—especially if they’re not cleaned or are turned off for a period of time.
And despite the Safe Drinking Water Act in 1974 and EPA standards for clean water, water can become contaminated with bacteria while being frozen and stored from ice making machines or from contact with other contaminated food.
A 2011 study by researchers at the University of Nevada, Las Vegas examined the prevalence of bacteria in ice and soda dispensed at Las Vegas restaurants. The study found that 33.3% of ice samples contained heterotrophic bacteria—higher than EPA standards. It also found that “72.2% were positive for presumptive coliform bacteria presence.” (The soda samples fared far worse in both categories.)
And of course, there’s human negligence. Bartenders who work while sick, don’t wash their hands before scooping ice, and use their hands to touch ice can contaminate ice from their hands. (Norovirus can be spread this way.)
“Most people don’t realize that not washing their hands could cause death,” Debra Huffman, a microbiologist at the University of South Florida, explained to NBC News in 2006. “They just don’t see the risk. It’s not going to smell funny. It’s not going to look funny. These are microscopic, and so you’re not going to see it. You wouldn’t known it happened.”