A new study has warned passengers against drinking coffee or tea on US airlines, citing potentially unsafe water in onboard tanks. Research by the Center for Food as Medicine and Longevity analysed 35,674 water tests reported to the Environmental Protection Agency (EPA) between October 2022 and September 2025, finding contamination in nearly three per cent of samples.
Samples taken from galley faucets and bathroom sinks tested positive for coliforms (2.66%) and E. coli (0.09%), the latter indicating faecal contamination that can cause stomach cramps, diarrhoea, and pneumonia. Airlines are required to disinfect and flush water tanks four times a year, but the study noted that stagnation between flights and temperature changes can still lead to contamination from airport hoses and tanks.
Among major carriers, American Airlines scored a D grade (1.75 out of 5), while JetBlue and Spirit also received Ds. Delta and Frontier earned top marks with As and scores of 5.0 and 4.8 respectively. Regional airlines fared worse: Mesa Airlines got an F (1.35), while GoJet Airlines was the only regional carrier to achieve a B grade.
Dr Charles Platkin, director of the centre, advised: “Never drink any water onboard that isn’t in a sealed bottle and do not drink coffee or tea onboard. Do not wash your hands in the bathroom – use alcohol-based hand sanitiser containing at least 60% alcohol instead.” He noted that nearly all regional airlines need to improve their water safety.
American Airlines responded, stating its potable water programme is fully compliant with EPA rules and that a recent EPA audit found no significant issues. The airline said it is reviewing the study’s methodology to determine potential enhancements. The independent research also identified incomplete EPA records that may mean the true contamination rate is higher than reported.
