Water: how much, and how to carry it
Water is a litre per kilogram. That single fact governs more trip planning than anything else on this site, and it is the one people consistently underestimate — partly because at home water is free and weightless, and partly because the cooking water is invisible until you are carrying it.
This guide is about quantity and carrying. For treating water of unknown quality — which method leaves which gap — see the water page.
Start from what you actually use
Drinking is the obvious part and often not the largest. Cooking is where the surprises are.
- Pasta wants a lot of water and most of it is poured away. You can cook it in far less than feels right; the starchier water is better for the sauce.
- Couscous and bulgur are frugal: roughly 1.2 times their volume.
- Rice takes a fixed ratio and the water goes into the food rather than down the drain.
- Dried pulses are the expensive ones. Roughly 2.4 litres per 500 g for the soak alone, before the fresh water they are boiled in — see rehydrating dried pulses.
- Washing up is a real line item, and one that shrinks a lot with a non-stick pan and a habit of wiping out rather than rinsing.
Add drinking on top of all of it, and more than you think in hot weather or after a hard day’s walking.
The arithmetic that decides dried versus tinned
This is the genuinely useful calculation and almost nobody does it.
A 400 g tin of chickpeas weighs about 450 g packed and needs no water at all.
The dried equivalent weighs perhaps 150 g in the bag — and then wants roughly 1.2 litres between soaking and cooking, plus the fuel to boil it twice.
So the dried version is heavier overall unless the water is already there. Which gives a clean rule:
Dried pulses are a good deal exactly when water is cheap.
- Carrying all your water, short trip: tins win outright.
- Refillable taps, longer trip: dried wins comfortably — the bag weighs nothing and the water is free at the tap.
- Sourcing and treating water: dried is expensive in a way that is easy to miss, because every litre now costs fuel or filter life.
Work out which of those three you are in before the shop, not after.
How to carry it
Rigid containers for the main store. Collapsible ones fail at the seams, and they fail when full, which is the worst possible moment and usually inside something.
Split the load. Two 10 litre containers beat one 20 litre container: easier to lift, easier to stow, and a failure costs you half rather than everything.
A tap is worth having if a container will live in one place. Pouring from 10 kg is how water ends up on the floor.
Keep one small bottle separate for drinking, so the main store is not opened constantly.
A collapsible carrier earns its place for refills, precisely because it packs flat empty — which is the state it spends most of its life in. Just not as the primary container. Options are on the kit page.
Where it lives
Low and central in a vehicle. Twenty kilograms of water high up changes how a van handles, and a container that shifts while moving will eventually find the one thing you did not want it to land on.
Out of the sun, which is about what grows in it rather than comfort. And if you are filling from anything other than a mains tap, read the treatment page first — the three methods fail in different places and the differences do not overlap.