Never Order Coffee On Airplanes, New Study Says

We already knew that flight attendants don't drink coffee or anything involving hot water on an airplane. In an anonymous interview with Business Insider, one flight attendant said that she did not believe that the water tanks in which hot water for things like coffee, tea, and bathroom sinks is stored are cleaned often enough. Now, thanks to a study from Hunter College's NYC Food Policy Center, it has been confirmed to be true.

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"Planes come in, [and the tanks are] not being emptied and cleaned, because there is no time for that. The water tank is being filled on top [after] each usage. Whatever would be on the bottom stays there and sits there," Charles Platkin, a professor of nutrition and the executive director of the Food Policy Center, told the New York Post.

Eleven airlines were polled about the nutritional value of their in-flight snacks and water tank procedures; airlines were asked about the key procedures used to clean water tanks, whether they check water tanks for contamination, and whether potable water systems are disinfected and flushed on a regular basis.

Delta and United say that they use a high-tech ozone disinfection process at least quarterly to clean their tanks, but Platkin says he isn't fooled. "They barely clean the planes in my opinion. I'm sure something that's hidden like the water is something that's not a huge priority."

"It's probably best to avoid drinking water from the tap on a plane, which also means staying away from coffee and tea," the Hunter College study concludes.

Hunter College's study is supported by a study from the Environmental Protection Agency, which found that one in eight airplanes nationwide do not meet their standards for water safety, and that 12 percent of commercial planes tested positive for fecal bacteria in the tap water supply. That means the water you wash your hands with in an airplane bathroom and the hot water that goes into your tea and coffee may contain some sort of fecal bacteria.

However, the trade association and lobbying group Airlines for America, which represents many large airlines, defended their water supply and hygienic standards: "Airlines work closely with the Environmental Protection Agency to ensure that water received from municipalities for onboard systems is safe and to maintain that safety by following rigorous sampling and management requirements once received," the group told Business Insider in a statement.

Airlines for America also added that bottled water is available to "meet customer preferences." Rancid tap water is just the tip of the in-flight iceberg. Here are 13 more things your flight attendant won't tell you.