How much water should you take on a hike?

How much water should you take on a hike? It seems like a simple question, but anyone who has ever put on a hiking backpack knows that the answer is rarely obvious. Taking too little water turns a pleasant outing into a headache. Taking too much water weighs on your shoulders, wastes energy, and disrupts your pace. Between these two extremes, there is an ideal range that depends on the hiker, the terrain, the climate, and the length of the hike. (Learning about these details before the hike makes a difference. If you like content about nature and planning, it's worth following our publications to gradually deepen your knowledge).

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This question is not exclusive to beginners. Even experienced hikers adjust their strategy according to the trail. On hot days, water seems to disappear from the bottle. On cold days, consumption decreases, but dehydration creeps up silently. The question everyone asks before leaving home is always the same: How much do I need to take?

Hiking seems like an activity with low logistical complexity, but it requires attention to the basics. Hydration is one of them. Ignoring water is more common than it seems. Most incidents on day hikes do not involve falls, animals, or sprains, but mild symptoms of dehydration. Dizziness, headache, irritability, nausea, cramps, and a feeling of low energy. People often attribute these signs to fatigue, when in fact the body is just asking for water replacement.

Hydration also influences cognitive performance. A trail requires constant decision-making. When to stop, when to speed up, when to put on an extra layer of clothing, when to deviate from the path. All of this worsens with dehydration. In natural environments, where the margin for error is small, this detail matters.

What the scientific studies indicate

In recent years, several research groups have begun to observe the behavior of hikers and mountaineers in real-life situations. Some studies focus on the volume of water ingested, others on the impact of heat, and others on physical and cognitive performance.

Despite methodological differences, there is convergence on one point. The human body loses more fluid during hiking than many people realize. In mild weather, the reference value found on day hikes is around 0.5 liters of water per hour of actual hiking. In hot weather, with moderate effort, the values rise to between 0.7 and 1 liter per hour. In very hot conditions, with long climbs or a fast pace, consumption can reach 1.5 liters per hour.

Another interesting fact. The way water is ingested influences the result. Drinking small amounts regularly works better than taking large gulps from time to time. Every 15 to 20 minutes is a benchmark used in research. This strategy promotes absorption, reduces gastrointestinal discomfort, and decreases the risk of going a long time without hydration.

Studies conducted in hot environments, similar to summer on the coast of Santa Catarina, have observed that hydration backpacks increase spontaneous consumption. When water is accessible, hikers drink more and at shorter intervals. This results in better water balance along the way. Interestingly, many hikers report that with bottles in their backpacks, they drink less simply because they don't want to stop, open, and get the water.

This is a detail that deserves attention. Mild dehydration, in the range of one to two percent of body weight, already impairs physical and cognitive performance. On trails with technical sections, this represents a real increase in risk. Even those who walk slowly notice this drop in performance when the trail requires focus, especially on steep descents, cliffs, or narrow sections. (If you enjoy studying this type of topic to better prepare yourself, our itineraries usually provide practical field information combined with science. It's a way to walk and learn without complicating things.)

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Water collection in nature 

So far, we have talked about the water that hikers carry with them. Now, let's turn our attention to the water that hikers find along the way. Some trails have streams, spouts, and springs. The idea of collecting water in nature is appealing. It reduces weight, saves space in your backpack, and strengthens your connection with the environment. However, there is an important caveat.

Relying exclusively on collection requires experience. Streams that flow strongly in the summer may be dry in the winter or during periods of drought. On some trails, water only appears after the halfway point. On others, the flow is weak and collection is difficult. There are trails where water is guaranteed most of the year and others where an untrained eye will pass right by collection points. You need to know the territory, observe signs in the landscape, and understand seasonality.

Even when there is water, it does not mean that it is safe for immediate consumption. Appearances can be deceiving. Microorganisms, parasites, and bacteria do not change color or smell. Animals also frequent the same sources. This does not mean that collecting water is prohibited, only that it requires treatment. Turning stream water into drinking water is an essential step.

There are several strategies for this. Boiling, filtration, and sanitizing tablets are the most common. At Família na Trilha, we use 'Clorin' for practicality. (This is not an advertisement!). It is light, efficient, and fast, especially when trail time matters. Regardless of the strategy, the logic is the same. Collecting water is only an advantage when done responsibly and with technique.

Another point that is rarely mentioned. Even if contaminated water does not cause immediate symptoms, gastrointestinal infections can appear days later. For those who are traveling, with consecutive trails or a tight schedule, this ruins their plans. Therefore, beginners should consider water collection as a supplement, not as their sole source. The key is still to leave home with enough water for the conditions of the trail.

How to calculate how much to take with you

One of the best ways to plan hydration is by time, not distance. Two kilometers on flat terrain can take less than half an hour. Two kilometers of uphill climbing on a technical trail can take over an hour. Time explains hydration better than mileage.

Three steps help: First, estimate the actual walking time. If the trail takes four hours under normal conditions, that's what should go into the calculation. Second, apply the reference value. In mild weather, 0.5 liters per hour. In hot weather or moderate exertion, between 0.7 and 1 liter per hour. Third, include a safety margin of 0.5 to 1 liter. This margin covers unforeseen events, extra stops, detours, and changes in pace.

A simple example: A four-hour hike in the heat.

Applying 0.75 liters per hour, the estimated consumption is three liters. With a margin, between 3.5 and 4 liters. This amount may scare beginners, but it makes sense when we consider the loss of fluids in hot and humid environments.

Another detail: Not everyone consumes the same amount. Slower people consume more over time because they are more exposed to heat. People who are less fit consume more because they exert more effort. People who carry heavy backpacks also increase their water consumption. On family hikes, children hydrate better with hydration backpacks than with bottles because they remember to drink more often.

Examples of trails in Florianópolis and the surrounding area

Local practice helps to visualize the calculation. In Lagoinha do Leste, the classic route leaving Pântano do Sul is five kilometers long with short climbs and exposed sections. On hot summer days, planning for two liters is the reasonable minimum. If the hiker intends to climb Morro da Coroa, consumption increases. On the crossing from Armação to Pântano, passing through Morro da Coroa, three to four liters makes sense.

On the Costa da Lagoa, the route can exceed seven kilometers. The most common mistake is to underestimate the time. For three to four hours of walking, one to two liters works well. There are shops, but relying on them alters the pace and is not suitable for those who do not want to stop.

In Naufragados, the trail to the beach is 3.5 kilometers long. Those who continue on to Forte Marechal Moura face exposed stretches on the rocky coast. For a round trip, between 2.5 and 3.5 liters is sufficient. There are shops on the beach and collection points along the way, but always with the same warning: planning is necessary.

On the Brazilian Way of St. James, the 22 kilometers alternate between trails, beaches, and urban stretches. In this case, water planning needs to be more careful. Being supplied before the Rapa and Feiticeiras trails avoids difficulties. In the other stretches, shops reduce the load, but frequent stops break the rhythm.

Conclusão

Planejar a água não é uma das tarefas mais simples do pré-trilha e uma das que mais influenciam a experiência. Segurança começa antes de pisar na mata. A hidratação adequada melhora o raciocínio e a tomada de decisão. Também permite observar mais, aprender mais e aproveitar a trilha com presença.

For most single-day hikes around Florianópolis and the nearby areas, two liters is sufficient under normal conditions. On very hot days, long trails, or trails with steep climbs, three liters are more appropriate. Collecting water can reduce weight, but only with technique, treatment, and an understanding of seasonality. The most important thing is not the exact number, but rather understanding the factors, planning with a margin, and drinking regularly.

The trail begins with planning. Water is one of the simplest and most important decisions you make before leaving home. (And if the idea is to put this knowledge into practice safely and with environmental interpretation, our guided tours are a good starting point. If you want to know which trails we are doing this week, contact us on WhatsApp and we will advise you without obligation.)

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SOURCE: Consensus