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SESK: Stuff Everyone Should Know · sesk.info/hike-water-loss-per-hour

On a hot, hard hike, how much water can a hiker lose through sweat in one hour?

One or two quarts an hour, which is why extra water is one of the Ten Essentials.

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  1. About a tablespoon
  2. One or two quarts ✔
  3. Three or four gallons

Why: Hawaii Volcanoes National Park warns hikers can lose one or two quarts of water per hour through heavy sweating. Losing that much without drinking leads to dehydration and heat exhaustion.

Huh, didn't know that: A quart is just under a liter, so two quarts is about as much as a big soda bottle.

The dad joke
Why did the water bottle go on every hike? It did not want to be left high and dry.
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References

Answer: One or two quarts. Hawaii Volcanoes National Park warns hikers can lose one or two quarts of water per hour through heavy sweating. Losing that much without drinking leads to dehydration and heat exhaustion.

  1. NPS Hawaii Volcanoes: Hiking Tips www.nps.gov/havo/planyourvisit/hike-tips.htm
    Hikers can lose one or two quarts (liters) of water per hour.
    Checked 2026-10-12.

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