Route & Budget 12 min read May 30, 2026

Water and food on long-distance trek: planning resupply with no blind spots

On a 7+ day trek, no backpack is ever big enough to carry all the water and food. Autonomy becomes a timing question: where and when to resupply? Reading frame to plan without blind spots.

3–4 L/d

water consumed daily in temperate trek

3,500–5,000 kcal/d

energy need in mountain

600–800 g/d

realistic daily resupply weight

5–7 d

standard resupply interval on long trails

Water chain: sources, filtration, carried capacity

• Confirmed sources — prefer mapped, seasonally confirmed points (refuges, fountains). Beware of trail sources in dry summers.
• Filtration — 0.1 μm micro-filter (Sawyer Squeeze ~55 g) covers 99.9% of cases except chemically polluted water.
• Carried capacity — 1.5 L minimum between two confirmed sources; 3 L in arid zone or long stage.

Food chain: caloric density and windows

• Target density — ≥4 kcal/g to optimise weight (freeze-dried, nuts, dried fruit, dark chocolate).
• Resupply windows — village stores (limited days/hours), poste-restante mail drops, cooked bivouacs (refuges).
• Safety margin — +1 day of ration minimum, +2 if unstable season or variant routes.

5-step planning method

1. Trace the route, mark all water sources and resupply points.
2. Compute distance and elevation between each logistical point.
3. Estimate water and caloric draw per profile (climate, elevation, break frequency).
4. Identify at-risk segments (resupply interval > 5 days, unconfirmed sources).
5. Decide: carry, mail-drop, or adjust the route.

Key takeaways

Plan for 3–4 L of water per day on temperate treks and 3,500–5,000 kcal/d in the mountains: two chains to plan in parallel.
Filter by default with a 0.1 μm micro-filter (Sawyer Squeeze ~55 g), covering 99.9% of cases except chemically polluted water.
Carry 1.5 L minimum between two confirmed sources, 3 L in arid zones or long stages.
Target a food density of ≥4 kcal/g and keep +1 day of ration minimum (+2 in an unstable season).
Beyond 5–7 days (≈3.5–5 kg at 700 g/day), intermediate resupply beats carrying everything.

FAQ

Should mountain spring water always be filtered?

Yes by default, even at altitude: giardiasis and cryptosporidiosis exist even in zones reputed clean. Filtration adds 55 g for an eliminated risk.

Max food weight to carry without breakdown?

Practical: 5–7 days at 700 g/day = 3.5–5 kg. Beyond, intermediate resupply becomes more efficient than portage.

Do mail drops work in France for long trails?

Yes via poste-restante (15-day hold) or refuges that accept prepaid parcels. Check destination post office opening hours.