This Study Will Make You Rethink Drinking Airplane Water (Yes, Even Coffee!)

I’ve always thought that airplanes had a strange smell. Not bad, per se, but off in some way, perhaps some combination of fuel, cleaning product, and recycled air. Once you start thinking about airplane air, it’s easy to move on to water. An aircraft can’t have the same pipes and plumbing as a building, so can its tap water be trusted? 

Right before the new year, the Center for Food as Medicine and Longevity (CFML) released its 2026 Airline Water Study, which examined 21 airlines operating in the U.S. and assessed the quality of the drinking water each one offers to its passengers. I’m sorry to say, but the results may not make you very thirsty.

To determine the water quality provided on board various airlines that serve the U.S., the Center for Food as Medicine and Longevity (CFML) took its time analyzing Environmental Protection Agency (EPA) data from October 2022 to September 2025. Airplane water was last assessed in 2019, eight years after the Aircraft Drinking Water Rule (ADWR), aka the first law mandating safe drinking water on planes, was passed. Those results showed that although water quality had improved since 2012, it was still largely not very good anywhere.

The 2026 study looked at 11 regional airlines and 10 major airlines, grading each from A to F based on their “Water Safety Score.” A score of 3.5 or better would earn a grade A or B. This score was based on five factors: any violations per aircraft, maximum contamination level violations for E. coli, indicator-positive rates, public notices, and disinfecting and flushing frequency. Ultimately, only two out of 21 airlines — Delta and Frontier — got an A grade.

I’m sure you don’t just want to know about how many airlines had poor-quality drinking water and/or inadequate measures to deal with contaminations like E. coli. Here’s everything the CFML found.

Major airline water quality grades, from best to worst: 

1. Delta – A
2. Frontier – A
3. Alaska Airlines – B
4. Allegiant Air – B
5. Southwest – C
6. Hawaiian Airlines – C
7. United – C
8. Spirit – D
9. JetBlue – D
10. American Airlines – D

Regional airline water quality grades, from best to worst: 

1. Gojet Airlines – B
2. Piedmont Airlines – C
3. Sun Country Airlines – C
4. Endeavor Air – C
5. SkyWest Airlines – D
6. Envoy Air – D
7. PSA Airlines – D
8. Air Wisconsin Airlines – D
9. Republic Airways – D
10. CommuteAir – D
11. Mesa Airlines – F

The study also found that “civil penalties for ADWR violations remain extremely rare if at all,” adding that they were “not able to get an answer” from the EPA about it. This may explain the high number of poor scores.

Only five out of 21 airlines scored a B grade or higher in the Airline Water Study, and even the airlines with A grades can’t necessarily be trusted to be consistent because of the EPA’s poor enforcement record. Due to this, the CFML’s official position on the matter is to “NEVER” — and they do spell it with all caps — “drink any water on board that isn’t in a sealed bottle,” which yes, includes coffee and tea. (Those mini cans of soda are safe, but maybe skip the ice.)

It isn’t just drinking water you should be wary of, either; the CFML recommends avoiding even the water from the plane’s bathroom sink, suggesting instead “hand sanitizer containing at least 60% alcohol.” Why so cautious? Per the CFML, “The potential health consequences of consuming contaminated aircraft drinking water ranges from acute gastrointestinal illness to exposure to opportunistic pathogens.” If you ask me, that’s enough to make me remember to bring my refillable water bottle (or spring for that Smartwater) the next time I fly.