Airline water: Which airline's water is safest at 35,000 feet? New study rates health of water provided to passengers

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Center for Food As Medicine & Longevity

Jan 05, 2026, 11:00 ET

Delta & Frontier Airlines The Safest Water in the Sky

American Airlines, JetBlue The Worst

NEW YORK, Jan. 5, 2026 /PRNewswire/ -- A 2026 Airline Water Study released this week by the Center for Food as Medicine & Longevity reveals that the quality of drinking water varies significantly by airline, and many airlines continue to provide passengers with potentially unhealthy water.

Unhealthy water violates the federal government's Aircraft Drinking Water Rule (ADWR), which was implemented in 2011 and requires airlines to provide passengers and flight crew with safe drinking water.

The 2026 Airline Water Study ranks 10 major and 11 regional airlines by the quality of water they provided onboard flights during a three-year study period (October 1, 2022 through September 30, 2025). Each airline was given a "Water Safety Score" (5.00 = highest rating, 0.00 = lowest) based on five weighted criteria, including violations per aircraft, Maximum Contaminant Level violations for E. coli, indicator-positive rates, public notices, and disinfecting and flushing frequency. A score of 3.5 or better indicates that the airline has relatively safe, clean water and earns a Grade A or B.

"Delta Air Lines and Frontier Airlines win the top spots with the safest water in the sky, and Alaska Airlines finishes No. 3," says Charles Platkin, PhD, JD, MPH, director of the Center for Food as Medicine and Longevity.

The airlines with the worst score are American Airlines and JetBlue, the study shows. "Nearly all regional airlines need to improve their onboard water safety, with the exception of GoJet Airlines," Platkin says.

The ADWR requires airlines to take samples from their water tanks to test for coliform bacteria and possible E. coli. Airlines are also required to 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 2026 Airline Water Study also finds 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.

Here are the study's findings:

The major airlines receiving the highest Water Safety Scores are Delta Air Lines (5.00, Grade A) and Frontier Airlines (4.80, Grade A). Alaska Airlines is a close third at 3.85 (Grade B).
GoJet Airlines is the highest-rated regional carrier with a score of 3.85 (Grade B).
Among major airlines, American Airlines has the lowest score of 1.75 (Grade D).
Nearly all regional airlines have poor Water Safety Scores. Mesa Airlines has the lowest score among rated regional carriers at 1.35 (Grade F), and CommuteAir is second-lowest at 1.60 (Grade D). CommuteAir shows an alarming 33.33% total coliform positive rate.
The study window analyzed 35,674 total sample locations tested for total coliform bacteria across all airlines. Of these, 949 locations (2.66%) tested positive for total coliform.
Maximum Contaminant Level violations for E. coli were identified as the strongest downward driver of airline scores. There were 32 such violations across the 21-airline universe during the study window.
The "Shame on You" Award goes to the EPA for weak enforcement. The study shows that civil penalties for ADWR violations remain extremely rare.
Testing for coliform bacteria is important, because their presence in drinking water indicates that disease-causing organisms (pathogens) could be in the water system.
When an aircraft's water sample tests positive for coliform, it must be tested again to determine if E. coli is present. If E. coli is not present, the airline must take repeat samples within 24 hours, disinfect and flush the water system within 72 hours, or shut down the water system within 72 hours and then disinfect and flush. If the sample is E. coli positive, the airline must shut off public access to the water system within 24 hours and disinfect and flush.
The ADWR does not require the same testing as the National Primary Drinking Water Regulations, which includes other microorganisms in addition to total coliform.
An aircraft flies to numerous destinations and may pump drinking water into its tanks from various sources at domestic and international locations. The water quality onboard also depends on the safety of the equipment used to transfer the water, such as water cabinets, trucks, carts and hoses.

Here's the bottom-line advice from the Center for Food as Medicine and Longevity. To be extra safe:

NEVER drink any water onboard that isn't in a sealed bottle.
Do not drink coffee or tea onboard.
Do not wash your hands in the bathroom; use alcohol-based hand sanitizer containing at least 60% alcohol instead.

Airline Water Safety Scores At-a-Glance (5.00 = highest rating, 0.00 = lowest):

Major Airlines

Delta Air Lines: 5.00 (Grade A)
Frontier Airlines: 4.80 (Grade A)
Alaska Airlines: 3.85 (Grade B)
Allegiant Air: 3.65 (Grade B)
Southwest Airlines: 3.30 (Grade C)
Hawaiian Airlines: 3.15 (Grade C)
United Airlines: 2.70 (Grade C)
Spirit Airlines: 2.05 (Grade D)
JetBlue: 1.80 (Grade D)
American Airlines: 1.75 (Grade D)

Regional Airlines

GoJet Airlines: 3.85 (Grade B)
Piedmont Airlines: 3.05 (Grade C)
Sun Country Airlines: 3.00 (Grade C)
Endeavor Air: 2.95 (Grade C)
SkyWest Airlines: 2.40 (Grade D)
Envoy Air: 2.30 (Grade D)
PSA Airlines: 2.25 (Grade D)
Air Wisconsin Airlines: 2.15 (Grade D)
Republic Airways: 2.05 (Grade D)
CommuteAir: 1.60 (Grade D)
Mesa Airlines: 1.35 (Grade F)

Airline Water Study Results

Major Airlines

Delta Air Lines
Water Safety Score: 5.00 / Grade A
Aircraft Fleet Size: 1,028
Total ADWR Violations (Oct 2022-Sept 2025): 9
Avg # of ADWR Violations per Aircraft: 0.01
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 0
Total Coliform Positive Rate: 0.47%
Indicator Positive Rate (total coliform with E. coli absent): 0.47%
Public Notices per 100 Aircraft: 0.19
Comments: Delta shows no Maximum Contaminant Level violations for E. coli and the lowest indicator-positive rate among all major airlines. Excellent performance across all metrics.

Frontier Airlines
Water Safety Score: 4.80 / Grade A
Aircraft Fleet Size: 171
Total ADWR Violations (Oct 2022-Sept 2025): 1
Avg # of ADWR Violations per Aircraft: 0.01
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 2
Total Coliform Positive Rate: 1.37%
Indicator Positive Rate: 1.05%
Public Notices per 100 Aircraft: 0.58
Comments: Frontier shows very low violations per aircraft and no Maximum Contaminant Level violations for E. coli.

Alaska Airlines
Water Safety Score: 3.85 / Grade B
Aircraft Fleet Size: 288
Total ADWR Violations (Oct 2022-Sept 2025): 8
Avg # of ADWR Violations per Aircraft: 0.03
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 0
Total Coliform Positive Rate: 0.88%
Indicator Positive Rate: 0.88%
Public Notices per 100 Aircraft: 2.08
Penalty Applied: Yes (alternative not clearly provided on at least one public notice)
Comments: Alaska shows no Maximum Contaminant Level violations for E. coli and a low indicator-positive rate, with one public notice response penalty reducing the overall score.

Allegiant Air
Water Safety Score: 3.65 / Grade B
Aircraft Fleet Size: 141
Total ADWR Violations (Oct 2022-Sept 2025): 9
Avg # of ADWR Violations per Aircraft: 0.06
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 4
Total Coliform Positive Rate: 1.31%
Indicator Positive Rate: 0.56%
Public Notices per 100 Aircraft: 1.42
Maximum Contaminant Level Violations for E. coli: 1
Comments: Allegiant has one Maximum Contaminant Level violation for E. coli, which is treated as a serious signal in the scoring model.

Southwest Airlines
Water Safety Score: 3.30 / Grade C
Aircraft Fleet Size: 914
Total ADWR Violations (Oct 2022-Sept 2025): 30
Avg # of ADWR Violations per Aircraft: 0.03
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 6
Total Coliform Positive Rate: 1.18%
Indicator Positive Rate: 1.06%
Public Notices per 100 Aircraft: 1.31
Maximum Contaminant Level Violations for E. coli: 5
Comments: Southwest shows multiple Maximum Contaminant Level violations for E. coli, a high-severity driver in the score.

Hawaiian Airlines
Water Safety Score: 3.15 / Grade C
Aircraft Fleet Size: 65
Total ADWR Violations (Oct 2022-Sept 2025): 48
Avg # of ADWR Violations per Aircraft: 0.74
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 0
Total Coliform Positive Rate: 4.31%
Indicator Positive Rate: 4.31%
Public Notices per 100 Aircraft: 10.77
Comments: Hawaiian shows high violations per aircraft and an elevated indicator-positive rate.

United Airlines
Water Safety Score: 2.70 / Grade C
Aircraft Fleet Size: 1,063
Total ADWR Violations (Oct 2022-Sept 2025): 105
Avg # of ADWR Violations per Aircraft: 0.10
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 7
Total Coliform Positive Rate: 2.38%
Indicator Positive Rate: 2.21%
Public Notices per 100 Aircraft: 0.00
Maximum Contaminant Level Violations for E. coli: 6
Comments: United shows multiple Maximum Contaminant Level violations for E. coli and an indicator-positive rate above the major-airline group average.

Spirit Airlines
Water Safety Score: 2.05 / Grade D
Aircraft Fleet Size: 248
Total ADWR Violations (Oct 2022-Sept 2025): 37
Avg # of ADWR Violations per Aircraft: 0.15
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 1
Total Coliform Positive Rate: 4.75%
Indicator Positive Rate: 4.67%
Public Notices per 100 Aircraft: 20.97
Maximum Contaminant Level Violations for E. coli: 1
Comments: Spirit shows an elevated indicator-positive rate and very high public notices per 100 aircraft.

JetBlue Airways
Water Safety Score: 1.80 / Grade D
Aircraft Fleet Size: 336
Total ADWR Violations (Oct 2022-Sept 2025): 220
Avg # of ADWR Violations per Aircraft: 0.65
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 6
Total Coliform Positive Rate: 5.67%
Indicator Positive Rate: 5.36%
Public Notices per 100 Aircraft: 8.63
Maximum Contaminant Level Violations for E. coli: 2
Comments: JetBlue shows a high violations-per-aircraft burden and an elevated indicator-positive rate.

American Airlines
Water Safety Score: 1.75 / Grade D
Aircraft Fleet Size: 995
Total ADWR Violations (Oct 2022-Sept 2025): 23
Avg # of ADWR Violations per Aircraft: 0.02
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 3
Total Coliform Positive Rate: 1.93%
Indicator Positive Rate: 1.86%
Public Notices per 100 Aircraft: 2.31
Maximum Contaminant Level Violations for E. coli: 3
Penalties Applied: Yes (alternative not clearly provided AND water system not clearly turned off on at least one public notice)
Comments: American's score is materially lowered by public notice response penalties and Maximum Contaminant Level violations for E. coli. American had the worst score among major airlines.

Regional Airlines

GoJet Airlines
Water Safety Score: 3.85 / Grade B
Aircraft Fleet Size: 58
Total ADWR Violations (Oct 2022-Sept 2025): 0
Avg # of ADWR Violations per Aircraft: 0.00
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 0
Total Coliform Positive Rate: 4.20%
Indicator Positive Rate: 4.20%
Public Notices per 100 Aircraft: 5.17
Comments: GoJet had zero ADWR violations and zero Maximum Contaminant Level violations for E. coli, receiving the highest score among regional carriers.

Piedmont Airlines (operates as American Eagle, owned by American Airlines)
Water Safety Score: 3.05 / Grade C
Aircraft Fleet Size: 81
Total ADWR Violations (Oct 2022-Sept 2025): 11
Avg # of ADWR Violations per Aircraft: 0.14
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 0
Total Coliform Positive Rate: 11.52%
Indicator Positive Rate: 11.52%
Public Notices per 100 Aircraft: 9.88
Comments: Despite having no E. coli violations, Piedmont shows an elevated indicator-positive rate.

Sun Country Airlines
Water Safety Score: 3.00 / Grade C
Aircraft Fleet Size: 46
Total ADWR Violations (Oct 2022-Sept 2025): 78
Avg # of ADWR Violations per Aircraft: 1.70
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 0
Total Coliform Positive Rate: 1.64%
Indicator Positive Rate: 1.64%
Public Notices per 100 Aircraft: 26.09
Comments: Sun Country has a very high violations-per-aircraft rate and elevated public notices.

Endeavor Air (operates as Delta Connection, owned by Delta Air Lines)
Water Safety Score: 2.95 / Grade C
Aircraft Fleet Size: 169
Total ADWR Violations (Oct 2022-Sept 2025): 10
Avg # of ADWR Violations per Aircraft: 0.06
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 1
Total Coliform Positive Rate: 1.65%
Indicator Positive Rate: 1.50%
Public Notices per 100 Aircraft: 6.51
Maximum Contaminant Level Violations for E. coli: 1

SkyWest Airlines
Water Safety Score: 2.40 / Grade D
Aircraft Fleet Size: 575
Total ADWR Violations (Oct 2022-Sept 2025): 1
Avg # of ADWR Violations per Aircraft: 0.00
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 3
Total Coliform Positive Rate: 2.06%
Indicator Positive Rate: 1.97%
Public Notices per 100 Aircraft: 10.96
Maximum Contaminant Level Violations for E. coli: 1
Penalty Applied: Yes (alternative not clearly provided on at least one public notice)

Envoy Air (operates as American Eagle, owned by American Airlines)
Water Safety Score: 2.30 / Grade D
Aircraft Fleet Size: 204
Total ADWR Violations (Oct 2022-Sept 2025): 24
Avg # of ADWR Violations per Aircraft: 0.12
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 4
Total Coliform Positive Rate: 1.62%
Indicator Positive Rate: 1.08%
Public Notices per 100 Aircraft: 6.37
Maximum Contaminant Level Violations for E. coli: 4

PSA Airlines (operates as American Eagle, owned by American Airlines)
Water Safety Score: 2.25 / Grade D
Aircraft Fleet Size: 121
Total ADWR Violations (Oct 2022-Sept 2025): 22
Avg # of ADWR Violations per Aircraft: 0.18
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 2
Total Coliform Positive Rate: 6.76%
Indicator Positive Rate: 6.35%
Public Notices per 100 Aircraft: 8.26
Maximum Contaminant Level Violations for E. coli: 1

Air Wisconsin Airlines (operates as United Express)
Water Safety Score: 2.15 / Grade D
Aircraft Fleet Size: 52
Total ADWR Violations (Oct 2022-Sept 2025): 28
Avg # of ADWR Violations per Aircraft: 0.54
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 1
Total Coliform Positive Rate: 3.91%
Indicator Positive Rate: 3.52%
Public Notices per 100 Aircraft: 23.08
Maximum Contaminant Level Violations for E. coli: 1

Republic Airways (operates as United Express, Delta Connection, American Eagle)
Water Safety Score: 2.05 / Grade D
Aircraft Fleet Size: 252
Total ADWR Violations (Oct 2022-Sept 2025): 201
Avg # of ADWR Violations per Aircraft: 0.80
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 2
Total Coliform Positive Rate: 2.44%
Indicator Positive Rate: 2.30%
Public Notices per 100 Aircraft: 5.16
Maximum Contaminant Level Violations for E. coli: 2

CommuteAir
Water Safety Score: 1.60 / Grade D
Aircraft Fleet Size: 65
Total ADWR Violations (Oct 2022-Sept 2025): 19
Avg # of ADWR Violations per Aircraft: 0.29
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 6
Total Coliform Positive Rate: 33.33%
Indicator Positive Rate: 32.21%
Public Notices per 100 Aircraft: 84.62
Maximum Contaminant Level Violations for E. coli: 2
Comments: Alarming. CommuteAir shows an exceptionally high total coliform positive rate (33.33%) and very high public notices per aircraft.

Mesa Airlines
Water Safety Score: 1.35 / Grade F
Aircraft Fleet Size: 101
Total ADWR Violations (Oct 2022-Sept 2025): 47
Avg # of ADWR Violations per Aircraft: 0.47
Total Water Samples Testing Positive For E. Coli (Oct 2022-Sept 2025): 2
Total Coliform Positive Rate: 6.10%
Indicator Positive Rate: 5.49%
Public Notices per 100 Aircraft: 18.81
Maximum Contaminant Level Violations for E. coli: 2
Comments: Mesa received the only failing grade among rated airlines, with poor performance across multiple metrics.

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About the Study

The 2026 Airline Water Study was conducted by the Center for Food as Medicine and Longevity using Aircraft Drinking Water Rule compliance, operational, sampling, and public notice records from the United States Environmental Protection Agency for the period October 1, 2022 through September 30, 2025. The study analyzed 35,674 total sample locations tested across 21 airlines.

Media Contacts:

Charles Platkin
Executive Director
[email protected]
Phone: 2123677575 ex 17

SOURCE Center for Food As Medicine & Longevity