- A new study by the Center for Food as Medicine and Longevity ranked major and regional airlines on the quality of their onboard tap water, analyzing more than 35,000 samples collected over three years.
- The results revealed vast differences among airlines, with some earning top marks for water safety and others, such as American and JetBlue, falling far behind.
- Researchers advise passengers to avoid drinking or using tap water for coffee, tea, or handwashing on flights, citing risks of microbial contamination from stagnant aircraft water systems.
There’s a lot of fantastic science and engineering that goes into making an airplane fly. Crew members are well-trained to ensure that travelers are both safe and comfortable. Ground crews work to keep us all moving from point A to point B as efficiently as possible. It’s certainly a solid effort by all, but that doesn’t mean there’s no room for improvement in air travel. And, as one new study found, that improvement could start with onboard water quality.
In late December, researchers from the Center for Food as Medicine and Longevity released the 2026 Airline Water Study, ranking 10 major and 11 regional airlines on the quality of water provided onboard. The study focuses on water available through faucets, not bottled water service.
To assess each airline’s water quality, the team collected 35,674 water samples over a three-year study period from October 1, 2022, to September 30, 2025. Each airline was then assigned a “Water Safety Score” from 0 to 5, based on five weighted criteria, including violations per aircraft and maximum contaminant level violations for E. coli. The team noted that any score above 3.5 indicates that the airline has “relatively safe, clean water and earns a Grade A or B.”
| Airline water safety scores: major carriers | |||
|---|---|---|---|
| RANK | AIRLINE | SCORE | GRADE |
| 1 | Delta Airlines | 5.00 | A |
| 2 | Frontier Airlines | 4.80 | A |
| 3 | Alaska Airlines | 3.85 | B |
| 4 | Allegiant Air | 3.65 | B |
| 5 | Southwest Airlines | 3.30 | C |
| 6 | Hawaiian Airlines | 3.15 | C |
| 7 | United Airlines | 2.70 | C |
| 8 | Spirit Airlines | 2.05 | D |
| 9 | JetBlue | 1.80 | D |
| 10 | American Airlines | 1.75 | D |
After analyzing all the samples, the researchers named Delta Airlines as having the “safest water in the sky” after scoring a perfect 5 on the assessment. It was followed closely by Frontier Airlines, which scored 4.80, placing it well within the Grade A category. Alaska Airlines rounded out the top three with a score of 3.85 (Grade B). According to the team, the worst-performing major airlines were American Airlines and JetBlue, both of which received a D grade.
But those grades are nothing compared to how the regional airlines fared. “Nearly all regional airlines need to improve their onboard water safety, with the exception of GoJet Airlines,” Dr. Charles Platkin, the center’s director, said. According to the findings, Mesa Airlines has the lowest score at 1.35 (Grade F), and CommuteAir is second-lowest at 1.60 (Grade D). Additionally, “CommuteAir shows an alarming 33.33% total coliform positive rate,” which could indicate the presence of disease-causing organisms in the onboard water system.
| Airline water safety scores: regional carriers | |||
|---|---|---|---|
| RANK | AIRLINE | SCORE | GRADE |
| 1 | GoJet Airlines | 3.85 | B |
| 2 | Piedmont Airlines | 3.05 | C |
| 3 | Sun Country Airlines | 3.00 | C |
| 4 | Endeavor Air | 2.95 | C |
| 5 | SkyWest Airlines | 2.40 | D |
| 6 | Envoy Air | 2.30 | D |
| 7 | PSA Airlines | 2.25 | D |
| 8 | Air Wisconsin Airlines | 2.15 | D |
| 9 | Republic Airways | 2.05 | D |
| 10 | CommuteAir | 1.60 | D |
| 11 | Mesa Airlines | 1.35 | F |
As for what you should take away from these findings, the researchers said you should “never” drink any water on a flight unless it came from a sealed bottle. That includes coffee or tea made with tap water. Additionally, you should not wash your hands with tap water; use “alcohol-based hand sanitizer containing at least 60% alcohol” instead.
And if you’re wondering how airplane water can get so nasty, the researchers explained that unlike your municipal water, which has a “continuous flow and regular monitoring,” aircraft water systems are often stagnant (think of times between flights) and experience temperature variations from ground to takeoff, cruising, descent, and landing, creating environments “conducive to biofilm formation and microbial proliferation.”
It should be noted that all airlines are technically responsible for providing clean, potable water onboard under the Aircraft Drinking Water Rule. However, the study found that the Environmental Protection Agency (EPA) rarely, if ever, issues citations for water violations. So bring hand sanitizer and fill your water bottle before you fly, just in case.
