Airline water quality study shows wide variation in drinking water safety aboard flights

A new 2026 Airline Water Study from the Center for Food as Medicine and Longevity reveals significant differences in tap water quality across U.S. airlines and highlights ongoing concerns about compliance with the Aircraft Drinking Water Rule (ADWR). The three-year analysis examined more than 35,000 water samples collected from onboard drinking water systems between October 2022 and September 2025, assigning each airline a “Water Safety Score” based on contaminant violations, E. coli detection, disinfecting and flushing practices, public notices, and other factors.

Major carriers Delta Air Lines and Frontier Airlines topped the rankings, each earning a Grade A with the highest Water Safety Scores, while American Airlines and JetBlue scored the lowest among major carriers, both receiving Grade D ratings. Among regional operators, GoJet Airlines was the highest-rated with a Grade B, but most regional airlines earned lower grades and lagged behind in water safety performance.

“Delta Air Lines and Frontier Airlines win the top spots with the safest water in the sky, and Alaska Airlines finishes No. 3,” said Charles Platkin, PhD, JD, MPH, director of the Center for Food as Medicine and Longevity, in an article. “Nearly all regional airlines need to improve their onboard water safety, with the exception of GoJet Airlines.”

The ADWR requires airlines to sample aircraft water tanks for total coliform bacteria and, where detected, test for E. coli, disinfect and flush systems regularly, and provide alternative water sources when contamination is confirmed. The study also found that civil penalties for ADWR violations are rarely imposed, a gap critics say weakens regulatory incentives.