You might think grabbing a quick beverage during your flight is harmless. Maybe even comforting. Something is lurking in those cups and cans though, and those who work behind the beverage carts know the truth better than anyone else. Let’s be real, they’ve seen what happens when passengers make the wrong choices at cruising altitude, and the consequences aren’t pretty.
Coffee And Hot Tea Made From Airplane Water
A comprehensive study examining over 35,000 water samples from 21 airlines revealed that many carriers serve potentially unhealthy water to passengers, with researchers specifically recommending travelers avoid drinking coffee or tea made with aircraft tap water. The situation is worse than most people realize. Out of 35,674 samples tested between 2022 and 2025, nearly 950 came back positive for coliform bacteria, and researchers detected 32 E.coli violations across the airlines during the study period.
Flight attendants themselves avoid hot beverages on board because water heaters are rarely cleaned unless they’re broken. Think about that for a moment. The tanks storing water on planes face stagnation between flights, temperature swings, and maintenance challenges that create perfect breeding grounds for bacteria. Among major U.S. airlines, American Airlines, JetBlue and Spirit earned a D rating for water quality, while Delta and Frontier received A grades.
Alcoholic Beverages
Here’s the thing about that glass of wine or cocktail you’re considering. Before you even take a sip, your blood oxygen drops from normal levels of 96 to 100 percent down to about 90 percent at cabin pressure equivalent to 6,000 to 8,000 feet above sea level. Research found that people who drank before falling asleep in simulated cabin pressure had their blood oxygen saturation drop to 85 percent, while their heart rates rose to nearly 88 beats per minute to compensate.
The dehydration factor makes things exponentially worse. Alcohol is a diuretic that accelerates dehydration, and the decrease in pressure when flying can enhance the negative effects of alcohol. Honestly, it’s not worth the risk. According to the International Air Transport Association, alcohol factors into 27 percent of reported disruptive passenger incidents, which speaks volumes about what happens when people underestimate how booze hits differently up there.
Diet Sodas And Drinks With Aspartame
Flight attendants have another concern that rarely gets discussed openly. Diet drinks containing aspartame create unique problems at altitude. Several pilots have reported troubling symptoms after consuming products with this artificial sweetener while flying. Some experienced dizziness, tremors, and what they described as an unsettling feeling that something wasn’t quite right.
The science behind this is alarming. Cabin pressure already reduces oxygen availability in your bloodstream. When you add aspartame to the mix, you’re potentially compounding effects that mimic hypoxia symptoms. Flight attendants dislike when passengers order Diet Coke because fizzy drinks are hard to pour at altitude, slowing down service, and soda can be pretty dehydrating. Sure, maybe the service angle matters to crew members trying to work efficiently, yet the health implications run deeper than convenience.
Ice In Your Drinks
That innocent-looking ice cube floating in your beverage? It came from the same contaminated water system we just discussed. Health experts explicitly recommend never drinking any water onboard that isn’t in a sealed bottle, and they also suggest skipping onboard coffee and tea while using alcohol-based hand sanitizer instead of washing hands with airplane sink water.
The water used to make ice passes through aircraft plumbing systems that refill from multiple airport sources worldwide. Water sits in enclosed tanks and narrow lines running through the fuselage, and as aircraft cycle through rapid altitude and temperature changes with mechanical vibrations, biofilms and bacteria can build up, particularly when planes sit idle between flights. Those cubes might look clean and refreshing, but appearances deceive at 35,000 feet.
Carbonated Beverages Of Any Kind
Fizzy drinks like soda and sparkling water lead to bloating and discomfort because trapped gas expands in the stomach during flight, and they can also contribute to heartburn, leaving passengers feeling sluggish and unsettled upon landing. Your digestive system already struggles with the altitude change. Adding carbonation to that equation is asking for trouble.
Changes in cabin pressure combined with reduced oxygen levels can inhibit the stomach from emptying and slow down digestion, meaning food takes longer to pass into the small intestine, which leads to bloating, trapped wind, and nausea. I know it sounds crazy, but that innocent can of club soda you ordered might be the reason you’re miserable for the rest of your journey. The gas expands as pressure decreases, turning your stomach into an uncomfortable balloon situation nobody wants to experience in a cramped seat.
High-Sodium Drinks Like Tomato Juice
Savory drinks like tomato juice and bloody Mary mix may taste extra delicious in the air due to altitude impacting taste buds, but these drinks can contain lots of sodium. Weird how our taste perception changes up there, right? The problem is that sodium accelerates dehydration in an environment already working against your hydration levels.
The cabin air is dry and lacks moisture with very low humidity, making it easier to become dehydrated. Piling on salty beverages when your body desperately needs water is counterproductive. Flight attendants have watched countless passengers down multiple tomato juices thinking they’re making a healthy choice, only to end up with pounding headaches and exhaustion hours later. The irony is that what tastes better at altitude might actually be what your body needs least.
What you choose to drink at 35,000 feet matters more than most travelers realize. Those of us who’ve spent years working flights have seen the patterns emerge. Stick with sealed bottled water whenever possible, and save the other beverages for when you’re safely back on solid ground. Your body will thank you for it. Did you think twice about that complimentary coffee before reading this?
