How much water should you drink on a 10 hour flight?

December 13, 2025 •

4 min read

With cabin humidity often comparable to a desert, experts and airline staff generally recommend drinking about 8 ounces of water for every hour spent in the air. This means that to combat dehydration and feel your best, you need to be mindful of how much water should you drink on a 10 hour flight.

Quick Summary

This guide breaks down the recommended fluid intake for a 10-hour flight, explains why airplane cabins cause rapid dehydration, and offers practical tips for maximizing hydration and minimizing discomfort.

Key Points

Consume 80 ounces of water: For a 10-hour flight, this is the recommended total based on consuming 8 ounces per hour.
Sip, don't chug: Drinking water steadily throughout the flight is more effective than large gulps, which can lead to frequent, unnecessary restroom trips.
Avoid alcohol and caffeine: These are diuretics that accelerate dehydration, counteracting your water intake.
Pack a reusable water bottle: This makes it easy to stay on track and get refills from flight attendants.
Consider electrolytes: Supplements can enhance hydration by replenishing key minerals lost in the dry cabin air.
Moisturize externally: Use lotion, lip balm, and nasal spray to combat the physical effects of dry cabin air on skin and mucous membranes.
Eat hydrating foods: Fresh fruits and vegetables are excellent snacks for adding water and nutrients.
Stand and stretch regularly: Moving around helps with circulation and allows for natural breaks to drink water and use the restroom.

The Scientific Reason for In-Flight Dehydration

While on the ground, most people don't think about humidity levels, but at cruising altitude, the cabin air is extremely dry. Recycled cabin air has a humidity level of only 10-20%, which is significantly lower than the 30-65% found in typical indoor environments on the ground. This arid environment leads to increased 'insensible water loss' through breathing and skin evaporation. For a 10-hour flight, this can result in the loss of up to 2 liters of water for men and 1.6 liters for women.

Additionally, the lower oxygen levels at altitude can cause your body to breathe faster, further accelerating moisture loss. The combination of low humidity, low oxygen, and static sitting conditions puts your body at a heightened risk for dehydration and associated side effects like headaches, fatigue, and dry skin.

The 10-Hour Flight Hydration Plan

For a standard 10-hour flight, following the Aerospace Medical Association's recommendation of 8 ounces of water per hour is a solid starting point. This translates to a total of 80 ounces (or about 2.4 liters) over the entire flight. The key is to sip consistently rather than chugging large amounts at once, which can overwhelm your system and lead to frequent, unproductive bathroom trips.

Recommended In-Flight Hydration Schedule for a 10-Hour Flight

During Boarding & Takeoff (First hour): Drink 8 ounces (1 cup) of water.
Every Hour In-Flight (Hours 2-9): Sip 8 ounces (1 cup) of water each hour. Set a watch or phone alarm as a reminder.
Pre-Landing (Hour 10): Drink the final 8 ounces (1 cup) of water.

This schedule ensures a steady intake, giving your body time to absorb and utilize the fluid effectively. For those who find plain water unappealing, herbal teas or electrolyte mixes can be great alternatives. Just be aware of the source; experts advise against drinking airplane tap water due to sanitation concerns.

Avoiding Dehydrating Beverages and Foods

While it's tempting to relax with a cocktail or stay alert with coffee, many popular in-flight beverages actively work against your hydration efforts. Understanding which drinks to avoid and why is critical for a comfortable long-haul flight.

Comparison of In-Flight Beverages


Beverage	Effect on Hydration	Why to Limit or Avoid
Water	Highly hydrating	No negative effects; best choice for combating dry cabin air.
Herbal Tea	Hydrating	Non-caffeinated options like chamomile can be soothing and relaxing.
Electrolyte Drink	Highly hydrating, replenishes minerals	Helps balance electrolytes lost due to low pressure and dry air.
Coffee / Caffeinated Tea	Diuretic, dehydrating	Increases urine output, counteracting the water intake. Can also disrupt sleep patterns.
Alcohol	Diuretic, highly dehydrating	Expands blood vessels, increasing urine output and worsening dehydration. The effects are amplified at altitude.
Sodas	Can be dehydrating due to high sugar content	Sugar increases urination and can lead to bloating due to carbonation and cabin pressure.

Additional Tips for Optimal Hydration

In addition to conscious water intake, several other strategies can help you arrive feeling fresh and rested.

Start Pre-Hydrating: Begin increasing your fluid intake in the 24 hours leading up to your flight. This gives your body a head start on battling the dry cabin air.
Wear a Mask or Use a Spray: Breathing through a mask can help humidify the air you breathe. A saline nasal spray can also keep your nasal passages moist and help prevent minor nosebleeds caused by dryness.
Moisturize Your Skin: The dry air can also pull moisture from your skin. Applying a quality moisturizer and lip balm frequently can help. For long-haul flights, some travelers even use a facial mist.
Eat Water-Rich Foods: Pack snacks like fresh fruit (cucumber slices, melon, or grapes) or small salads. These foods provide extra water and electrolytes.
Stand and Stretch: Don't avoid getting up to use the restroom. Moving around every few hours improves circulation and helps prevent issues like deep vein thrombosis (DVT), in addition to allowing for a hydration break.

The Importance of Electrolytes

While water is crucial, some studies suggest that supplementing with electrolytes can be even more effective for hydration on long flights. The low-pressure environment can affect your body's mineral balance. Electrolyte mixes or tablets, which contain essential minerals like sodium and potassium, can be added to your water to improve fluid retention and overall well-being.

Conclusion

For a 10-hour flight, the recommended intake is roughly 80 ounces (about 2.4 liters) of water, sipped steadily over the duration. This strategy, combined with avoiding dehydrating drinks like alcohol and coffee and incorporating hydrating snacks, is the best way to prevent the fatigue, headaches, and dry skin associated with long-haul travel. Prioritizing hydration from before takeoff to landing ensures you arrive at your destination feeling refreshed and ready to enjoy your trip.

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Frequently Asked Questions

Airplane cabins have extremely low humidity, often 10-20%, which is significantly drier than on the ground. This dry air causes the body to lose moisture faster through breathing and skin evaporation, accelerating dehydration.

While regular water is essential, some studies suggest that an electrolyte beverage can be more effective for hydration on long flights. Electrolytes help the body absorb and retain fluids better, which is beneficial in the low-pressure cabin environment.

Pre-hydrating is a good strategy but should not replace in-flight hydration. The ongoing fluid loss in the cabin requires consistent replenishment. A large pre-flight intake won't sustain you for 10 hours and may just lead to a few early bathroom trips.

No, avoiding the restroom is not recommended. Frequent trips to the lavatory are a good indicator you are hydrating sufficiently. It also encourages movement, which is important for preventing blood clots on long-haul flights.

Snack on water-rich foods like cucumber, watermelon, grapes, or a light salad. These foods contribute to your overall fluid intake and help combat the dehydrating effects of the cabin environment.

It is not advisable to drink beverages made with airplane tap water. Studies have found that water tanks on planes can harbor bacteria. It is best to stick to bottled water or herbal tea prepared with sealed, bottled water.

You can use a saline nasal spray to keep nasal passages moist, apply a moisturizing lotion and lip balm to your skin, and use a facial mist periodically. These external hydration methods help soothe the drying effects of the cabin air.