Airplane Water Quality Remains Unsafe Across Multiple Carriers: Report

Researchers warn that aircrafts often carry stagnant water in their storage tanks, pulled from regional supplies whose quality can vary greatly.

A new water quality study found that many major and regional airlines serve drinking water contaminated with bacteria during domestic and international flights.

According to research published by the Center for Food as Medicine & Longevity, onboard water provided by 60% of major U.S. airlines tested failed to meet federal safety standards. American Airlines received the lowest overall safety score among major carriers, followed closely by JetBlue and Spirit Airlines.

The findings come from the 2026 Airline Water Study, which assessed the quality of drinking water served on flights operated by 10 major and 11 regional airlines over a three-year period from October 1, 2022, to September 30, 2025.

Researchers evaluated water violations related to the federal government’s Aircraft Drinking Water Rule (ADWR) implemented in 2011. Each airline was given a “water safety score” between 0 and 5, the highest rating. The ranking is based on five criteria: violations per aircraft, maximum contaminant level violations for E. coli, positive rates, public notices, and disinfecting and flushing frequency.

Samples were also taken from water tanks and tested for coliform bacteria and possible E. coli. The study analyzed 35,674 total sample locations tested for total coliform bacteria across all airlines. A score of 3.5 or better indicates the airline has relatively safe water, earning the airline a Grade A or B.

While the scores varied significantly between airlines, many airlines provide unhealthy water for drinking, coffee and hand washing.

According to the findings, of the more than 35,000 locations tested, 949 were positive for coliform. Across the 21 airlines tested, there were 32 violations during the three-year period, with E. coli violations being the number one contributor for lowering airlines scores.

Under the ADWR, airlines do not have to conduct the same strict testing that is done on municipal water systems and do not test for microorganisms other than coliform, since aircraft do not have continuous flow like municipal systems. This means the water is often stagnant, the researchers noted.

Additionally, airplanes fly to numerous destinations and pump drinking water into the tanks from different domestic and international sources. Water quality can vary based on the equipment used to transfer water like trucks, carts, hoses and cabinets. Water is then stored in onboard tanks that experience fluctuating temperature and pressure.

The U.S. Environmental Protection Agency (EPA) is responsible for ensuring safe aircraft drinking water. However, the agency rarely fines airlines in violation of the ADWR.

Water Safety Scores

Air flight is an essential mode of transportation for hundreds of millions of passengers every year in the United States, yet aircraft water systems allow for many opportunities for microbes to form and contamination to occur. Moreover, regulations do not require frequent flushing or disinfection.

Airlines are required to flush and disinfect aircraft water tanks four times per year, or they can choose to flush and disinfect the tanks once a year and conduct monthly testing instead. However, there is no data on whether airlines are conducting the required testing.

American Airlines, JetBlue and Spirit Airlines rounded out the bottom three worst major airlines all with scores of 1.75, 1.80 and 2.05 respectively. Delta scored the highest of the major airlines with a 5 score and grade A.

The data showed nearly all regional airlines needed to improve water quality and safety. GoJet received the highest safety score at 3.85, while Mesa Airlines received the lowest, at 1.35.

The Center for Food as Medicine & Longevity advised passengers flying on U.S. aircraft to never drink any water onboard that is not in a sealed bottle. Passengers should also avoid drinking coffee or tea since it is made with aircraft water. The center also warned to use soap when washing your hands in the bathroom and to use an alcohol-based hand sanitizer containing at least 60 percent alcohol afterward.

Sign up for more health and legal news that could affect you or your family.