The study was conducted by the nonprofit organization Center for Food as Medicine and Longevity over a three-year period. Researchers analyzed data collected between Oct. 1, 2022, and Sept. 30, 2025, reviewing water samples from 10 major and 11 regional airlines. In total, the study examined 35,674 sample locations, focusing on “violations per aircraft, Maximum Contaminant Level violations for E. coli, indicator-positive rates, public notices, and disinfecting and flushing frequency.”
Each airline received a Water Safety Score based on five weighted criteria, with scores ranging from 0 to 5.00. A score of 3.5 or higher indicated relatively safe water and earned a grade of A or B, while anything below that threshold was considered unsafe for consumption.
Here’s what the study found.
Which Airline Has the Safest Water?
So, which airlines came out on top? According to the study, Delta Air Lines and Frontier Airlines ranked highest, each earning a water safety score of 4.50 or above.
Alaska Airlines and Allegiant Air also met the water safety standards, earning grades of B.
