How Much Water Should You Bring for a Hike?
Plan for about 0.5 liters (17 oz) per hour of hiking as a starting baseline.
Quick answer
How Much Water Should You Bring for a Hike?
Carry about 0.5 liters (17 ounces) of water per hour of moderate hiking, and more in heat, at altitude, or on steep terrain. Sip steadily rather than waiting until you are thirsty: thirst only begins at roughly 1-2% body-mass loss, by which point you are already mildly dehydrated and aerobic performance starts to decline (Popkin 2010).
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Proper hydration is critical for safe and enjoyable hiking. The general guideline is to carry about 0.5 liters (17 ounces) of water per hour of moderate hiking activity. However, this increases significantly with hot weather, high altitude, strenuous terrain, and heavy pack weight. For a full day hike, plan to carry or have access to 2-4 liters minimum. Running out of water on a trail is one of the most dangerous situations hikers face, so always err on the side of bringing too much.
Factors That Increase Water Needs
Hot Weather
In temperatures above 80°F, increase water to 0.75-1 liter per hour. Heat dramatically increases sweat rate and can quickly lead to dangerous dehydration on the trail.
High Altitude
Above 5,000 feet, you lose water faster through breathing and increased urination. Add 0.5-1 liter extra per day for every 5,000 feet of elevation gain.
Steep Terrain
Uphill hiking significantly increases exertion and sweat rate. Steep descents also require more effort than flat terrain. Plan for 0.75 liters per hour on difficult trails.
Heavy Pack Weight
Carrying a heavy backpack increases calorie and water expenditure. For backpacking trips with 30+ pound packs, increase water intake by about 25%.
Trail Hydration Tips
- Pre-hydrate by drinking 16-20 oz of water 1-2 hours before starting your hike
- Sip water every 15-20 minutes during the hike rather than waiting until you are thirsty
- Bring electrolyte tablets or powder for hikes longer than 2 hours or in extreme heat
- Know where water sources are on the trail and carry a filter or purification method
- Weigh yourself before and after a hike to gauge fluid loss and adjust future planning
Medical Disclaimer: This content is for informational purposes only and does not constitute medical advice. Hiking in extreme conditions without adequate water is dangerous. Always tell someone your hiking plan and bring more water than you think you need.
Sources & Citations
- 1-2% body-mass loss — Thirst is initiated at roughly 1-2% body-mass loss, the level at which adverse physical and mental effects begin, so by the time you feel thirsty you are already mildly dehydrated.[1]
- 2% or more body-mass loss — Dehydration at or above 2% body-mass loss impairs thermoregulation, increases cardiovascular strain, and reduces aerobic performance, with decrements observed at as little as 2%.[1]
- more than 2% body mass — Across 33 studies, dehydration significantly impaired attention, executive function, and motor coordination, with greater impairment once the deficit exceeds about 2% body mass.[2]
- Ucol 1-3 hydrated, 4-6 hypohydrated, 7+ dehydrated — On the validated Armstrong urine color chart, colors 1-3 indicate good hydration, 4-6 indicate hypohydration, and 7 or higher indicates dehydration, so dark urine is a sign to drink.[3]
- Ucol >=4; sensitivity 87.8%, specificity 64.3%, AUC 0.831 — A self-assessed urine color of 4 or higher detects elevated urine osmolality (underhydration) with high sensitivity.[4]
- [1]Popkin 2010 — Popkin BM, D'Anci KE, Rosenberg IH. Water, hydration, and health. Nutr Rev. 2010;68(8):439-458.PMID: 20646222DOI: 10.1111/j.1753-4887.2010.00304.x
- [2]Wittbrodt 2018 — Wittbrodt MT, Millard-Stafford M. Dehydration Impairs Cognitive Performance: A Meta-analysis. Med Sci Sports Exerc. 2018;50(11):2360-2368.PMID: 29933347DOI: 10.1249/MSS.0000000000001682
- [3]HPRC (US DoD) — Human Performance Resources by CHAMP (HPRC), Uniformed Services University / US Department of Defense. How to Accurately Assess Hydration Status Using Urine Color Charts.
- [4]Perrier 2016/2017 (PMC5383926) — Perrier ET, Bottin JH, Vecchio M, Lemetais G. Criterion values for urine-specific gravity and urine color representing adequate water intake in healthy adults. Eur J Clin Nutr. 2017;71(4):561-563.PMID: 28145416DOI: 10.1038/ejcn.2016.269
Last reviewed: 2026-06-21. Every figure on this page is sourced to the named primary references above.
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Frequently Asked Questions
How much water for a 5-mile hike?
For a moderate 5-mile hike taking about 2-3 hours, bring at least 1-1.5 liters. In hot weather or hilly terrain, bring 2 liters. It is always better to have extra.
Can I drink from streams while hiking?
Never drink untreated water from streams. Even clear-looking water can contain Giardia, bacteria, and other pathogens. Always filter, boil, or chemically treat backcountry water.
Is a hydration bladder better than water bottles?
Hydration bladders are convenient because you can drink while moving. Water bottles are easier to track how much you have consumed. Many hikers use a combination of both.
What are signs of dehydration on the trail?
Watch for dark urine, headache, dizziness, fatigue, dry mouth, and decreased coordination. If you notice these signs, stop, rest in shade, and drink water immediately.
Should I bring sports drinks for hiking?
For hikes over 2 hours, electrolyte drinks or supplements are beneficial. They replace sodium and potassium lost through sweat. Electrolyte tablets that dissolve in water are lightweight and convenient.
How do I carry enough water for a long hike?
Use a combination of a hydration bladder (2-3 liters) and water bottles. For long backcountry hikes, carry a water filter and plan your route around water sources.
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