How to stay properly hydrated during a trek or long-distance hike
· Elodie Belleudy
How to stay properly hydrated during a trek or long-distance hike
Dehydration is the leading cause of hikers abandoning their routes. Yet, most hikers underestimate their needs, especially in cool weather when sweating is less noticeable.
The basic figures to know
The ANSES recommends drinking 1.5 to 2 liters of water per day under normal conditions. When hiking, this figure increases significantly depending on exertion and temperature. The French Alpine Club recommends 500ml per hour of exertion in temperate conditions, and up to 1 liter per hour in hot conditions or at high altitude.
On a 6-hour hike, this represents 3 to 6 liters of water, an amount impossible to carry in traditional bottles without considerably weighing down your pack.
The signs of dehydration to recognize
Thirst is a late signal: by the time you feel it, you are already slightly dehydrated. The first signs to watch for:
- Unusual fatigue and a sudden drop in motivation
- Headaches, even mild ones
- Dark urine (orange or brown), a sign of advanced dehydration
- Difficulty concentrating and irritability
- Muscle cramps often linked to the loss of minerals
Dehydration of just 2% of body weight reduces physical performance by 20% according to sports studies. On a trail run or trek, that makes all the difference.
The golden rule: drink before you get thirsty
Mountain guides and experienced trail runners all follow the same rule: drink regularly, in small sips, every 15 to 20 minutes, without waiting until you are thirsty. This habit maintains constant hydration and prevents fatigue spikes.
Ultratrailer tip: set an alarm every 20 minutes on your GPS watch at the start. After a few outings, the reflex becomes automatic.
Identify water points along the route
On marked GR routes in France, refuges and gîtes d'étape are reliable water points. On less frequented trails, you need to plan ahead. The AllTrails and Komoot apps allow you to identify springs and fountains on the route.
Remember, however: even a spring indicated on a map can be contaminated depending on the season, nearby animal activity, or recent weather conditions. A filtering bottle turns any water source into a safe one without waiting or handling.
The strategy of water self-sufficiency
Trekkers who cover long distances on the GR20, Tour du Mont-Blanc, and Camino de Santiago (shoutout to @darkvadrouille on Insta) have all developed the same strategy: a filtering bottle as the main source, supplemented by a hydration bladder for long stages.
This combination allows you to resupply at any clean stream without depending on supply points. Instead of planning your day around potable fountains, you can focus on your path.
A 650ml bottle covers more than an hour of intense exertion and can be refilled in a few seconds at any spring, river, or fountain along the route.
The PEAK filtering bottle filters down to 0.1 microns. Lightweight and compact, it fits into any backpack.
Discover the ALPINE- ANSES — Nutritional recommendations for water consumption
- French Alpine Club — Guide to hydration at altitude
- Journal of Athletic Training — Effects of dehydration on sports performance
- AllTrails / Komoot — Outdoor mapping apps
Written by the DollyStarlight team.