The Reason Why You Can’t Drink Airplane Bathroom Water

You’re in the midst of a cross-country flight. Your water bottle is empty. Wishing to be environmentally friendly and not ask for another plastic container, you head to the airplane bathroom to refill it. Just before you take a sip, you see a sign cautioning you not to ingest the tap water. You return to your seat, parched. A baby begins screaming in your face. You sink into your seat.

While it’s true that air travel can cause mild dehydration—cabins are usually low in humidity, which can dry out your throat and sinuses—you shouldn’t be quenching your thirst from an airplane faucet. The reason? Airplane water is absolutely disgusting.

In a 2019 water quality analysis conducted by Hunter College NYC Food Policy Center at the City University of New York and consumer advocacy site Diet Detective, water retrieved from major airlines was found to be contaminated with E. coli as well as other coliform bacteria. (Not all coliform bacteria is harmful, though its presence can indicate the existence of other, potentially dangerous pathogens.) The water, which is stored in onboard tanks, is sourced from a variety of locations depending on when the tanks need to be refilled. The water may also be housed or transported in containers that don’t adhere to any sanitary policies.

Because these channels are either poorly supervised or not at all monitored, there’s no system by which water brought on board a plane can be assessed for pathogens. Nor is there any reliable protocol for airlines to frequently clean the water storage tanks. The net result? Dirty tap water that few would recommend for drinking. And yes, that includes the coffee and tea made with tank water.

In fact, many experts are wary of using an airplane bathroom faucet even for handwashing, though that may be unavoidable depending on one’s activities. (Hand sanitizer is recommended instead.)

So where’s the oversight? In 2011, the U.S. introduced the Airline Drinking Water Rule, which mandates regular testing for the presence of bacteria and cleaning of tanks. The Environmental Protection Agency (EPA) is in charge of monitoring water quality in planes but rarely levies fines when infractions are found. Worse, the regulations are largely self-governing: It’s up to airlines to collect their own samples, not a third party.

Since bacteria is present, it seems like we should be hearing more about water-related illness on planes—but experts may not always attribute outbreaks to the water supply. According to study author Dr. Charles Platkin, who spoke to HealthLine, it’s possible that water-related gastrointestinal illness is being erroneously blamed on airplane food. (Platkin added he “wouldn’t touch” airplane water.)

It’s best to stick to bottled water for drinking, and perhaps even bottled water for hand-rinsing if you want to be extra-careful or have a compromised immune system. There are plenty of things to like about traveling, but the in-flight water isn’t one of them.

Have you got a Big Question you’d like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.