How much water do you bring? Choosing the size per trip

How much water do you bring on the go? Too little and you run dry at an unfortunate moment, too much and you carry needless weight, because water is heavy. In this article we give practical rules of thumb to choose the right amount based on duration, distance and temperature, and we help you choose between 2 and 3 litres.

The basic rule of thumb

A common guideline is roughly half a litre of water per hour of moderate effort in average weather. In warm weather or brisk walking that can rise to three quarters of a litre up to a litre per hour. This is not an exact law, because body weight, pace and how quickly you sweat play a part, but it gives a good starting point.

Situation	Guideline per hour
Calm walk, mild weather	about 0.5 litre
Brisk trip or warm weather	0.75 to 1 litre
Short intensive effort	often more per hour

Convert it to your trip

Estimate how long you are out and multiply that by the guideline. A four hour day trip in mild weather asks for around two litres, the same trip on a warm day closer to three litres. Add a small reserve in case you are out longer or it gets warmer than expected.

Can you refill on the way?

An important question: do you pass a reliable refill point on the way? If so, you do not have to carry everything at once and can start lighter. If not, bring the full estimated volume plus reserve. On remote routes this is the difference between comfortable and getting into trouble.

2 or 3 litres?

For the choice between a 2 litre and a 3 litre water solution, roughly:

• 2 litres: short to medium trips, mild weather, or if you can refill
• 3 litres: long trips, warm weather, or routes without a refill point

But remember: water weighs about a kilo per litre. Three litres is therefore three extra kilos in your bag. Do not carry the maximum by default if you do not need it. Which form, bottle or bladder, is nicest is covered in carrying water on the go: bottle or bladder.

Distributing it smartly in your backpack

Water is heavy, so its place in your backpack matters. Store it close to your back and centrally, so the weight sits stable. More about smart packing is in packing a backpack for a day trip or journey. Take a look at the options in the water bottles and carriers.

Frequently asked questions

How much water should I bring while hiking?

Count about half a litre per hour in mild weather and up to a litre per hour in heat or intensive effort. Multiply that by the duration of your trip and add a small reserve.

Is 2 litres of water enough for a day trip?

For a shorter day trip in mild weather 2 litres is often enough, especially if you can refill. In warm weather or on a long route you are safer with 3 litres.

How long does water stay good in a hydration bladder?

In a clean bladder water stays drinkable for a few days, but taste and freshness decline. Refresh water before each trip and do not leave it sitting in the bladder long, certainly not in heat.

How much does water weigh in my backpack?

Water weighs about a kilo per litre. Three litres is therefore three extra kilos. Do not carry more than needed and store it close to your back for stability.