Airline Tap Water Found Unsafe for Coffee, Study Reports
• Updated
A recent study has revealed alarming concerns about the quality of tap water aboard commercial flights, raising questions about the safety of drinking coffee or tea prepared on planes. The 2026 Airline Water Study, conducted by the Center for Food as Medicine and Longevity, evaluated water quality across major and regional airlines, finding that bacteria contamination is a widespread issue.
Study Findings Highlight Unsafe Water
The study spanned three years, from October 1, 2022, to September 30, 2025, and involved 35,674 water sample tests from 10 major and 11 regional airlines. Researchers assessed the water for coliform bacteria, a sign of potential pathogen presence, and discovered 949 positive samples. Furthermore, 32 E. coli violations were detected across the airlines during this period. Contaminated water, particularly with E. coli, can cause severe health issues such as diarrhea, vomiting, and even kidney failure.
Airlines were ranked using a "Water Safety Score", with a scale of 0 to 5, where 5 indicates the best water quality. Delta Air Lines and Frontier Airlines achieved the highest scores, both earning a Grade A, while Alaska Airlines followed closely with a Grade B. Other airlines fell below the safety threshold of a score of 3.5, prompting concerns about the overall state of water quality.
Why Is Airplane Water a Risk?
The study points to systemic challenges with maintaining clean water on flights. While airline water originates from local ground or surface water sources, it is transferred to and stored in airplane water tanks that may not be cleaned frequently. Dr. Kelly Johnson-Arbor, a toxicologist at MedStar Health, explained that the tanks are often "topped-up between flights" rather than fully emptied and cleaned, creating an environment for bacteria to thrive.
"Microbial contamination can occur at various points during the transfer of water from the original source to the airplane", Johnson-Arbor said. Even the carafes used to store hot beverages might be cleaned using the same tap water, further compounding the risk of contamination.
Additionally, enforcement of federal regulations appears insufficient. The Environmental Protection Agency (EPA) oversees water quality standards for airlines under the Aircraft Drinking Water Rule (ADWR). However, the study noted that penalties for violations are rare, making compliance inconsistent across the industry.
Expert Advice for Travelers
Experts advise passengers to take precautions when consuming beverages on planes. Dr. Jamie Alan, an associate professor of pharmacology and toxicology at Michigan State University, emphasized the importance of planning ahead. "You can always just grab a coffee in the airport and bring it on board", Alan suggested.
Johnson-Arbor concurred, stating, "Flyers should maintain a heightened awareness of the potential dangers of water contamination on airplanes when using airline restrooms or consuming hot beverages on airplanes." She recommended avoiding coffee or tea made with airplane tap water unless bottled water is used in preparation.
Conclusion
The 2026 Airline Water Study serves as a stark reminder of the potential risks associated with consuming beverages prepared with airplane tap water. While some airlines have demonstrated superior water safety practices, many still fall short, leaving passengers vulnerable to exposure to harmful bacteria. To mitigate this risk, experts advise travelers to avoid drinking coffee or tea on flights unless they can verify that bottled water was used. By staying informed, passengers can prioritize their health while in the air.
