Ordering a cup of tea on a flight or splashing your face with water in the bathroom probably feels harmless. But a recent study is making people rethink these small inflight habits. It turns out that the water used on many planes may not be as clean as you think.
What The Study Actually Found
Between 2022 and 2025, researchers from the Center for Food as Medicine and Longevity carried out a massive study called the 2026 Airline Water Study. They tested over 35,000 water samples from 21 different US airlines, aiming to see how safe the onboard water really is.
The results were pretty eye-opening. Around 2.66 percent of the water samples showed signs of coliform bacteria, which is often linked to unsanitary conditions. Even more concerning, 32 samples tested positive for E. coli, a clear sign of fecal contamination. That’s the kind of bacteria you definitely don’t want in your coffee.
So how does this even happen? Unlike city tap water, which flows through constantly maintained systems, airplane brevage sits in tanks inside the aircraft. These tanks are filled and cleaned on the ground, but not always as regularly or carefully as they should be. Between long gaps in use, big changes in temperature and pressure, and aging plumbing systems, bacteria can easily grow inside.
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Not All Airlines Are Equal
The study didn’t just look at the water itself. It also gave each airline a score based on how well they followed federal water standards. Delta came out on top with a perfect 5.00, followed by Frontier Airlines at 4.80 and Alaska Airlines at 3.85.
But not every airline did well. According to the study, American Airlines scored just 1.75, and JetBlue got 1.80. Some smaller regional airlines had even worse results, including multiple cases of E. coli.
How To Play It Safe On Your Next Flight
So what should you do with all this info? The researchers recommend keeping it simple. Don’t drink tap water from the plane. That includes hot drinks like coffee and tea, since the water might not be heated enough to kill harmful bacteria.
Stick to sealed bottled water whenever you can. If you’re thirsty, ask the flight attendants for a bottle instead of using the bathroom sink or taking the hot drink cart for granted. It’s also a good idea to bring hand sanitizer and use it instead of washing your hands with tap supply from the lavatory.
And if you’re thinking about brushing your teeth mid-flight, it’s better to use bottled one for that too. It’s a small change that could save you from dealing with a nasty stomach bug while traveling.
