For business travellers, hydration is not a lifestyle preference it is a necessity. Long-haul flights, dehydrating cabin air and back-to-back meetings across time zones make water, tea and coffee part of the working day at altitude.
Yet few passengers give much thought to where that water actually comes from.
A new 2026 Airline Water Study suggests they probably should.
Conducted by the Centre for Food as Medicine & Longevity, the study analysed three years of federal water-quality data to assess how well airlines comply with the US Aircraft Drinking Water Rule, the regulation governing potable water onboard aircraft. The results reveal notable differences between carriers, with clear implications for frequent flyers.
Aircraft water is stored in onboard tanks and used for drinking, hot beverages and handwashing. While regulated, these systems are complex, subject to frequent refilling, and reliant on consistent maintenance. For business travellers who fly weekly, sometimes daily, small differences in compliance and cleanliness quickly add up.
Poor water quality can affect hydration, confidence in hot drinks, basic hygiene and overall wellbeing, particularly on long or multi-segment journeys.
The study reviewed 21 US airlines. While the full ranking is extensive, five major carriers emerged as consistent top performers for onboard water safety.
The top five airlines for water safety
1. Delta Air Lines
Delta leads the rankings, praised for robust water-quality management and reliable system maintenance. For business travellers, this means greater confidence when ordering tea or coffee, or simply washing hands mid-flight. On long-haul and transcontinental routes, that reassurance matters.
2. Frontier Airlines
Frontier takes second place, performing strongly across all safety indicators. Its ranking challenges assumptions that low-cost carriers cut corners on essential infrastructure, demonstrating that operational discipline, not ticket price, determines water quality.
3. Alaska Airlines
Alaska Airlines secures third place, reinforcing its reputation for consistency and operational reliability. For travellers moving between West Coast hubs or connecting through Seattle, its clean-water performance adds another tick in the box.
4. Allegiant Air
Allegiant may not be a traditional business-travel airline, but its strong showing is good news for travellers using regional routes and secondary airports. Solid water-quality practices help it outperform several larger competitors.
5. Southwest Airlines
Southwest completes the top five. While the study notes areas for improvement, it still ranks ahead of many peers, offering generally safe onboard water across one of the largest domestic networks in the United States.
What business travellers should take from this
For frequent flyers, especially those clocking up long days in the air, in-flight water quality is not a marginal concern. It directly affects:
• Hydration during multi-segment workdays
• Confidence in hot beverages such as tea and coffee
• Hygiene, particularly on long-haul flights
• Overall wellbeing during intensive travel schedules
The study underlines a simple but important reality: not all airlines manage water systems equally well. Carrier choice can influence health and comfort, not just punctuality or seat pitch.
Practical precautions still apply
Despite improved standards among top-ranking airlines, the researchers behind the study continue to advise caution. Passengers are encouraged to prioritise sealed bottled water where available and to use hand sanitiser rather than tap water in aircraft lavatories, sensible precautions regardless of airline.
For business travellers, awareness is key. As cabin experiences become increasingly scrutinised, from air quality to sleep ergonomics, water safety is emerging as another factor worth factoring into travel decisions.
At 35,000 feet, the details matter more than ever.