How Much Water to Carry Hiking

Water is the heaviest thing in most packs at roughly two pounds a litre. Carrying too little is dangerous and carrying too much is a self-inflicted problem, so the goal is carrying exactly enough to reach the next reliable source with a margin.

1. 1

   Start with the working rule

   Roughly half a litre per hour of moderate hiking in mild conditions. That is about one litre for a two-hour walk, two litres for a half day, and three to four litres for a full day between sources. Treat this as a starting point rather than a fixed number.

2. 2

   Adjust for heat and effort

   Heat, sustained climbing, and high exertion can double consumption. On a hot exposed day with significant climbing, a litre an hour is realistic. Altitude also increases fluid loss through faster breathing and drier air, which people consistently underestimate.

3. 3

   Plan by dry stretch, not by day

   What matters is the longest gap between reliable sources, not the daily total. If sources are frequent, carry one litre and refill often — that is far easier than carrying four all day. If the route has a ten-mile dry section, that section sets your capacity requirement.

   Choosing a filterMatching treatment to your sources

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4. 4

   Verify sources rather than trusting the map

   Mapped springs and seasonal creeks shrink or disappear by late summer. Recent trip reports and the managing agency are better sources than the map. Where a source is uncertain, plan as though it is dry and treat finding water as a bonus.

5. 5

   Replace salt as well as water

   Drinking large volumes of plain water while sweating heavily dilutes blood sodium, which can produce symptoms resembling dehydration. On long hot days, eat salty food or use an electrolyte product alongside the water rather than simply drinking more.

   Electrolytes explainedWhen salt matters as much as water

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6. 6

   Camp near water and carry less

   The single biggest weight saving available is camping within reach of a source, filtering in the evening and morning, and carrying only what you need between camps. Hauling a full day of water to a dry camp is occasionally necessary and rarely the best plan.

Rough Capacity by Conditions