Hydration on the Trail: How Much Water Do You Really Need?
Carry too little and you risk dehydration; carry too much and you're hauling kilograms you don't need. Here's how to get it right.
Water is the heaviest thing most hikers carry — one litre weighs one kilogram. Getting your hydration right is a balancing act between safety and comfort.
How much do you need?
There’s no single answer. A rough starting point is around half a litre per hour of moderate hiking in mild conditions, but that can double in heat, at altitude or on steep climbs. Your body size, fitness and sweat rate all matter.
The best guide is to watch your own signals:
- Urine colour: Pale straw is good. Dark yellow means drink more.
- Thirst: Drink little and often rather than waiting until you’re parched.
- Headaches and fatigue: Often early signs of dehydration.
Plan your water carries
Before you start, study your map for water sources and the distance between them. Then:
- Estimate how long each stretch will take.
- Multiply by your hourly need, adjusting for heat and climbing.
- Add a buffer — especially in the desert, where sources can be dry.
“Camel up” at each source: drink your fill before leaving, so you carry less.
Don’t forget electrolytes
On long, hot days, you lose salt as well as water. Drinking large amounts of plain water without replacing electrolytes can, in rare cases, lead to hyponatremia. Salty snacks or an electrolyte mix are an easy fix.
Treating water
Filters, chemical tablets, UV purifiers and boiling all work. Choose based on your trip: filters are fast and chemical-free; tablets are ultralight backups; boiling is reliable when you’re cooking anyway.
Hot weather tips
- Hike in the early morning and evening, and rest in the shade during the hottest hours.
- Wear a wide-brimmed hat and loose, light-coloured clothing.
- Soak your hat or bandana at water sources for evaporative cooling.