How to Stay Hydrated on a Long-Haul Flight
Why Long-Haul Flights Are So Dehydrating
Cabin air is notoriously dry — humidity levels on commercial aircraft typically sit between 10–20%, far below the 30–60% we're used to on the ground. At cruising altitude, your body loses moisture faster than you realise, and most passengers don't drink nearly enough to compensate.
The result? Fatigue, headaches, dry skin, and that groggy, jet-lagged feeling that can ruin the first day of any trip.
What Happens to Your Body at 35,000 Feet
Beyond the dry air, several other factors accelerate dehydration in-flight:
- Reduced air pressure causes your body to work harder to circulate oxygen, increasing fluid loss through respiration.
- Alcohol and caffeine — common in-flight choices — are diuretics that accelerate fluid loss.
- Immobility reduces circulation, making it harder for your body to distribute fluids efficiently.
- Salty snacks served on board draw water out of your cells, worsening dehydration.
The Electrolyte Advantage
Drinking plain water alone isn't always enough. Your body needs electrolytes — sodium, potassium, and magnesium — to absorb and retain fluid at the cellular level. Without them, you can drink litres of water and still feel dehydrated.
This is why pilots and cabin crew rely on electrolyte supplementation as a core part of their in-flight routine. Electrolytes help your body make the most of every sip.
Practical Hydration Tips for Long-Haul Flights
- Start hydrating before you board. Aim to be well-hydrated 24 hours before your flight, not just in the departure lounge.
- Drink 250ml of water per hour of flight as a baseline — more if you're in a dry cabin or have consumed alcohol.
- Add an electrolyte supplement to your water, especially on flights over 6 hours. Look for a formula with sodium, potassium, and magnesium.
- Avoid alcohol and limit caffeine — or at minimum, match each alcoholic drink with a full glass of water.
- Use a refillable bottle. Asking for water repeatedly is easy to forget; having a bottle in hand is a constant reminder.
- Moisturise and use a nasal spray to reduce moisture loss through skin and respiration.
A Pilot's Perspective
At Mach, our formulas were developed with the demands of flight crew in mind — people who spend hundreds of hours a year in pressurised cabins and need to perform at their best on arrival. The same principles that keep pilots sharp apply to every traveller: hydrate early, hydrate smart, and give your body the electrolytes it needs to function properly at altitude.
Whether you're crossing time zones for business or heading off on a long-awaited holiday, arriving hydrated makes everything better.