A new 2026 airline water quality study finds that water on U.S. flights still varies widely by airline. In some cases, airline water poses health risks to passengers.
The study, released today by Center for Food as Medicine and Longevity, analyzed federal compliance data across a three-year period and ranked 21 major and regional airlines based on the safety of the water served during flights. The results show sharp differences between carriers, with some earning top marks and others falling into failing territory.
The study was released over a decade after the federal government implemented the Aircraft Drinking Water Rule, which set safe water requirements for U.S. airlines. The law mandates regular testing for bacteria, including E. coli, along with routine disinfection and flushing of aircraft water tanks.
15 years later, some airlines are still providing unhealthy drinking water.
Best and Worst Airlines for Water Safety
It’s not all bad. Delta scored a 5.0 Water Safety Score—the highest numerical score possible—while Frontier earned a 4.80. Each airline was given a Grade A.
Alaska Airlines followed closely behind with a Grade B and a score of 3.85.
At the bottom of the rankings were American Airlines and JetBlue. American took home a poor 1.75 with a Grade D—handing the flight carrier the lowest score of major U.S. airlines.
Regional airlines get even worse. Nearly all scored poorly, with Mesa Airlines earning a Grade F and a 1.35 Water Safety Score.
“Delta Air Lines and Frontier Airlines win the top spots with the safest water in the sky,” said Charles Platkin, director of the Center for Food as Medicine and Longevity. “Nearly all regional airlines need to improve their onboard water safety.”
What the Study Found
The study reviewed water-quality data from October 2022 through September 2025, covering more than 35,000 onboard water samples reported to the Environmental Protection Agency.
Key findings include:
- Nearly 1,000 onboard water sample locations tested positive for total coliform bacteria—an indicator that harmful pathogens could be present
- 32 violations involved E. coli
- Regional airlines showed significantly higher contamination rates than major carriers
The study also found that enforcement of federal law was weak. According to the report, penalties for airlines that violate drinking water guidelines are rare or nonexistent.
Why Aircraft Water Is Vulnerable
Unlike municipal water systems, aircraft water is stored in tanks. This means it sits stagnant between flights, and is loaded across multiple airports using hoses, carts, and trucks. Contamination often occurs during servicing or when systems are not properly disinfected.
When water tests positive for bacteria, airlines are required by law to flush the system, disinfect it, and provide alternative drinking water to passengers. According to the study, some airlines failed to document corrective steps in those cases.
Advice for Passengers
Based on the findings, if you want to be absolutely safe, the Center for Food as Medicine and Longevity issued straightforward guidance for travelers:
- Do not drink onboard tap water
- Avoid coffee and tea on flights
- Use alcohol-based hand sanitizer instead of washing hands in the lavatory
- Stick to bottled water and other sealed beverages
Still, the findings are not a guarantee of water quality on any specific flight. Instead, it offers a clear signal on consistency: which airlines regularly perform better, and which airlines struggle to continually provide safe drinking water.
The New Jersey Digest is a new jersey magazine that has chronicled daily life in the Garden State for over 10 years.