A cup of tea or coffee at 40,000 feet may sound like a great way to give yourself an extra energy boost during a tiring trip, but it might be healthier to nap away your fatigue—or at least wait until hitting ground to indulge in a caffeine fix. Because, in addition to being tepid and watery, plane brew could be teeming with germs and other harmful life forms, according to Business Insider.

Multiple studies and investigations have taken a closer look at airplane tap water, and the results aren’t pretty—or appetizing. In 2002, The Wall Street Journal conducted a study that looked at water samples taken from 14 different flights from 10 different airlines. Reporters discovered “a long list of microscopic life you don’t want to drink, from Salmonella and Staphylococcus to tiny insect eggs," they wrote.

And they added, "Worse, contamination was the rule, not the exception: Almost all of the bacteria levels were tens, sometimes hundreds, of times above U.S. government limits."

A 2004 study by the U.S. Environmental Protection Agency (EPA) found that water supplies on 15 percent of 327 national and international commercial aircrafts were contaminated to varying degrees [PDF]. This all led up to the 2011 Aircraft Drinking Water Rule, an EPA initiative to make airlines clean up. But in 2013, an NBC investigation found that at least one out of every 10 commercial U.S. airplanes still had issues with water contamination.

Find out how airplane water gets so gross, and why turning water into coffee or tea isn’t enough to kill residual germs by watching Business Insider’s video below.

[h/t Business Insider]