Plan 4 liters per person per day for drinking, cooking, and cleaning, and carry a 20% reserve. That is roughly 1 gallon per person per day — the number most agencies publish — plus margin for heat, coffee, and washing up. Water is heavy (1 kg per liter), so the plan is as much about where you refill as how much you carry.
Daily need by condition
| Condition | Drinking | Cooking + cleaning | Total per person |
|---|---|---|---|
| Cool, sedentary | 2 L | 1.5 L | 3.5 L |
| Warm, light activity | 3 L | 1.5 L | 4.5 L |
| Hot or hiking | 4–6 L | 1.5 L | 5.5–7.5 L |
| Cold weather | 2.5 L | 2 L | 4.5 L |
Add 30% for children per body weight, and 1 L per hour of hard hiking in heat.
Sources: what you can trust
| Source | Reliability | Treatment needed |
|---|---|---|
| Campground tap | High | None |
| Ranger station / visitor center | High | None |
| Spring (marked) | Medium | Filter or boil |
| Creek / river | Medium | Filter or boil; avoid agricultural runoff |
| Lake | Medium | Filter; avoid near-shore algae |
| Stock tank | Low | Filter, and only in emergencies |
| Snow | Seasonal | Melt (fuel cost) |
Never plan on a source you have not confirmed. A dry spring on a map is a common surprise, and a 10-mile detour with 8 lb of water is a bad day.
Treatment: three methods
| Method | Removes | Time | Best for |
|---|---|---|---|
| Hollow-fiber filter (0.1–0.2 micron) | Bacteria, protozoa, microplastics | 1–2 L/min | Most camping |
| Boil (rolling 1 min) | Everything biological | 5–10 min + fuel | Groups, cloudy water |
| Chemical (chlorine dioxide) | Bacteria, viruses | 15–30 min | Backup, ultralight |
| UV (Steripen) | Bacteria, viruses, protozoa | 90 s/L | Clear water only |
Filters do not remove viruses; in North America that is rarely an issue, but in developing countries boil or use chemicals. A filter plus tablets is the standard two-layer approach.
Storage: containers by trip type
| Container | Capacity | Weight (empty) | Best for |
|---|---|---|---|
| Soft bladder | 2–3 L | 3–5 oz | Backpacking, drinking |
| Nalgene / hard bottle | 1 L | 6 oz | Everyday, hot water bottle |
| Collapsible jug | 5–10 L | 8–12 oz | Car camping, camp kitchen |
| Jerry can | 20 L | 2–3 lb | Basecamp, groups |
| Water cache (buried) | 10–20 L | — | Dry sections, pre-placed |
Keep drinking water separate from washing water so you never ration the wrong one. Label the washing jug.
Resupply window
| Trip | Carry | Resupply |
|---|---|---|
| Overnight, car camp | All of it | None |
| 2–3 days, campground taps | 1 day | Refill daily |
| 3–5 days, backcountry | 2–3 days | One cache or spring |
| 5+ days | 3 days max | Planned caches every 2–3 days |
A cache is a container you place in advance at a road crossing. Mark it, bury it in shade, and retrieve it on the way out — leaving it is littering.
Emergency reserve
Carry 2 L per person beyond the plan, untouched. It covers a dry source, a stove failure that forces cold food, or an unplanned night out. The reserve is not for coffee.
Carrying it: pack weight versus trips
Water is the heaviest thing most campers carry, and the trade-off is always the same: carry more and walk slower, or carry less and make trips.
| Carry | Weight | Range between sources |
|---|---|---|
| 2 L | 4.4 lb | 8–10 mi in cool weather |
| 4 L | 8.8 lb | 12–15 mi |
| 6 L | 13 lb | 18–20 mi |
| 10 L | 22 lb | Basecamp only |
A useful rule for dry sections: one liter per hour of hiking in heat, and plan the load so you arrive at the next source with about 1 L left. Arriving empty means the plan had no margin.
A water plan in five lines
- People × days × 4 L = base need.
- Check every source on the route; assume half are dry.
- Choose one primary treatment and one backup.
- Storage: 3 L drinking + 5 L washing per two people.
- Reserve: 2 L per person, sealed.
Where to go next
For filter specifications, see the water filter guide; for kitchen water use, the food and cooking guide; for hot-weather needs, the hot weather guide.
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