Ordering a coffee or tea mid-flight seems trivial. A new American study on water safety on airplanes shows, however, that the water used on board is far from always being impeccable, even on large companies.
Carried out between 2022 and 2025, the “2026 Airline Water Study” of the
Center for Food as Medicine and Longevity sifted through the waters of 21 American companies. Objective: measure the quality ofdrinking water on planes using a dedicated index and verify compliance with federal rules. The figures that emerge seriously question passenger confidence.
Drinking water on planes under surveillance
Each company received a Water Safety Score
between 0.00 and 5.00, a score of at least 3.5 meaning water considered relatively safe (grades A or B). Out of 35,674 sampling locations, 949 (2.66%) tested positive for
coliform bacteria. The researchers also identified 32 maximum level violations for
E.colian indicator of serious fecal contamination.
Among major carriers, Delta Air Lines gets a perfect score of 5.00 (A), ahead of Frontier Airlines (4.80, A) and Alaska Airlines (3.85, B). “Delta Air Lines and Frontier Airlines take the top spots with safest water in the sky, and Alaska Airlines comes in at number 3“, explains Charles Platkin, director of the Center for Food as Medicine and Longevity, in a press release. Conversely, American Airlines (1.75, D) and JetBlue (1.80, D) bring up the rear, while Mesa Airlines (1.35, F) and CommuteAir (1.60, D, including 33.33% positive coliform samples) illustrate the difficulties of regional airlines. “Almost all regional airlines need to improve their onboard water safety, except GoJet Airlines“, adds Charles Platkin.
Why airplane water remains difficult to secure
A plane does not have a continuous water network like a city. The water is pumped from different airports, stored in on-board tanks, then distributed to the galleys (aircraft kitchen areas) and toilets. The stagnation times between two flights, variations in temperature and pressure and the complexity of the plumbing favor the formation of biofilms and microbial proliferation, especially if the trucks, pipes and water cabinets used on the ground are imperfectly maintained.
American federal rule Aircraft Drinking Water Rulein force since 2011, requires regular coliform and E. coli, as well as disinfecting and flushing tanks four times a year (or once a year with monthly testing). In the case of coliforms, repeated samples must be taken within 24 hours, then the system disinfected, rinsed or closed within 72 hours; a positive result for E. coli requires the water to be turned off within 24 hours and the supply of alternative water. The study recalls that this rule remains less comprehensive than the general drinking water standards and that theEnvironmental Protection Agency very rarely imposes sanctions…
What to do to limit risks in flight
Faced with these observations, the authors provide very direct advice. “NEVER drink water on board that is not from a sealed bottle“, advises the Center for Food as Medicine and Longevity. The group also recommends avoiding hot drinks prepared with airplane water and choosing a hydroalcoholic gel at least 60% for hand hygiene, rather than water from the sinks.
Can we extrapolate these results for European or French companies? Everything suggests that the practices of these companies are not totally different… However, it is still very important to hydrate on a plane because the altitude tends to dry out your body. The solution to staying hydrated? Buy or request a bottle of water. This is the safest option. And for those who are thrifty, also remember to fill your bottle at the airport! Water fountains are sometimes made available after the control zones.