Nutrition
How Much Water to Bring on a Hike
Suggested amounts based on duration and heat, how to pace your drinking, and what to do about water from springs and streams.
As a guideline, plan on between 0.5 and 1 liter of water for every hour of hiking, increasing the amount in hot weather or on steep climbs. It's better to take small sips every 15 or 20 minutes than to drink a large amount at once. Never assume that water from natural springs or streams is safe to drink.
6 min read · updated September 14, 2026
As a practical guideline, plan on 0.5 to 1 liter of water per hour of hiking. The lower end of that range applies to mild weather and an easy pace; the upper end applies to heat, direct sun, or sustained climbs.
Suggested amounts
- 2-hour hike, mild weather: 1 liter.
- Half day (4–5 hours): 1.5–2 liters.
- Full day (7–8 hours): 2.5–3 liters.
- Summer, temperatures above 30 °C, or an exposed route without shade: add at least half a liter per planned hour.
These figures are a starting point, not a universal rule: water needs depend on your weight, pace, temperature, and humidity. Adjust based on your own experience and note how much you had left over or how much more you needed.
Drink before you feel thirsty
Thirst appears when you already have a fluid deficit. Take a few sips every 15–20 minutes instead of drinking half a liter all at once during a break. Start your hike already hydrated: drink half a liter in the hour before setting out.
Electrolytes, not just water
On long hikes in hot weather, you lose sodium through sweat. If you will be hiking and sweating for more than three or four hours, alternate water with an electrolyte drink or eat something salty. Drinking only water in large amounts without replacing electrolytes can cause discomfort, cramps, and, in extreme cases, hyponatremia.
Springs and streams
Do not assume any spring is reliable: springs may be dry in summer or unsafe to drink from. Check the official trail description or ask the local visitor center beforehand. If you plan to drink untreated stream water, treat it with a 0.1–0.2-micron filter, water purification tablets, or boiling. Always collect water upstream from pastures and trails.
Warning:Dizziness, headache, hot and dry skin, confusion, or nausea in hot weather may indicate heatstroke. Stop the activity, find shade, cool the person down, and call 112: this is a medical emergency, not just fatigue.
Sources and references
General safety information only. It does not replace specific mountain training or emergency services (112 in Spain and the EU).