Airline Water Quality Study Reveals E. coli Contamination On Major US Carriers

A three-year study released by the Center for Food as Medicine & Longevity reveals variations in drinking water quality across commercial airlines, with many carriers continuing to provide passengers with potentially unhealthy water that violates federal safety standards. The 2026 Airline Water Study examined compliance data from October 1, 2022, through September 30, 2025. The research ranked 10 major airlines and 11 regional carriers based on their adherence to the federal Aircraft Drinking Water Rule implemented in 2011.

The study analyzed 35,674 total sample locations across all airlines and found that 949 locations tested positive for total coliform bacteria, representing a 2.66 percent contamination rate. More alarmingly, the study identified 32 Maximum Contaminant Level violations for E. coli across the airline industry during the study period. According to Charles Platkin, PhD, JD, MPH, director of the Center for Food as Medicine and Longevity, “Delta Air Lines and Frontier Airlines win the top spots with the safest water in the sky, and Alaska Airlines finishes No. 3.”

Delta And Frontier Rank High While American Airlines And JetBlue Struggle

Delta Air Lines earned the highest Water Safety Score of 5.00 out of 5.00, receiving a Grade A for its drinking water quality, according to the study findings. Frontier Airlines secured second place with a score of 4.80, also earning a Grade A. Alaska Airlines finished third among major carriers with a score of 3.85 and a Grade B rating.

At the opposite end of the spectrum, American Airlines received the lowest score among major carriers at 1.75, earning a Grade D. JetBlue Airways scored only slightly higher at 1.80, also receiving a Grade D. Spirit Airlines rounded out the bottom three with a score of 2.05. Among regional carriers, GoJet Airlines performed best with a score of 3.85, while Mesa Airlines received the lowest rating at 1.35, earning a Grade F. The study notes that “nearly all regional airlines need to improve their onboard water safety, with the exception of GoJet Airlines.”

The study emphasizes that testing for coliform bacteria remains critical because “their presence in drinking water indicates that disease-causing organisms (pathogens) could be in the water system.” Maximum Contaminant Level violations for E. coli were identified as the strongest downward driver of airline scores. The study noted that “there were 32 such violations across the 21-airline universe during the study window.”

Weak EPA Enforcement Raises Concerns About Airline Water Safety Compliance

The study assigned a “Shame on You” designation to the Environmental Protection Agency for weak enforcement of the Aircraft Drinking Water Rule. The research shows that civil penalties for violations remain extremely rare, stating that “the Environmental Protection Agency — one of the federal agencies responsible for ensuring safe aircraft drinking water — rarely levies civil penalties to airlines in violation of the ADWR.”

The Aircraft Drinking Water Rule requires airlines to take samples from their water tanks to test for coliform bacteria and possible E. coli, as well as disinfect and flush each aircraft’s water tank four times per year. Alternatively, an airline may choose to disinfect and flush once a year, but then it must test monthly.

The center provides clear guidance to help passengers minimize health risks during air travel. Travelers should never drink any water onboard that is not in a sealed bottle. Coffee and tea prepared with onboard water should be avoided. Instead of washing hands in aircraft bathrooms, passengers should use alcohol-based hand sanitizer containing at least 60 percent alcohol.

Major Airlines Rankings

1. Delta Air Lines – Water Safety Score: 5.00, Grade: A
2. Frontier Airlines – Water Safety Score: 4.80, Grade: A
3. Alaska Airlines – Water Safety Score: 3.85, Grade: B
4. United Airlines – Water Safety Score: 3.30, Grade: C
5. Hawaiian Airlines – Water Safety Score: 3.15, Grade: C
6. Southwest Airlines – Water Safety Score: 2.75, Grade: C
7. Allegiant Air – Water Safety Score: 2.70, Grade: C
8. Spirit Airlines – Water Safety Score: 2.05, Grade: D
9. JetBlue Airways – Water Safety Score: 1.80, Grade: D
10. American Airlines – Water Safety Score: 1.75, Grade: D

Regional Airlines Rankings

1. GoJet Airlines – Water Safety Score: 3.85, Grade: B
2. Envoy Air – Water Safety Score: 3.20, Grade: C
3. Air Wisconsin – Water Safety Score: 3.15, Grade: C
4. PSA Airlines – Water Safety Score: 2.75, Grade: C
5. Republic Airways – Water Safety Score: 2.65, Grade: C
6. SkyWest Airlines – Water Safety Score: 2.60, Grade: C
7. Horizon Air – Water Safety Score: 2.45, Grade: D
8. Piedmont Airlines – Water Safety Score: 2.00, Grade: D
9. Endeavor Air – Water Safety Score: 1.85, Grade: D
10. CommuteAir – Water Safety Score: 1.45, Grade: F
11. Mesa Airlines – Water Safety Score: 1.35, Grade: F

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