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How Much Water Should I Bring On A Hike? (And How To Calculate It)

Too many times, hikers underestimate the amount of water they’ll need on the trail. Most beginners set out with the thought that it’s only a mile or two, but by the time they’ve crested their first hill, they’re wishing they had brought more water on their hike.

You should bring a minimum of 0.5 liters of water for every mile that you plan to hike. However, the amount of water you should bring may increase depending on the length of trail, type of terrain, elevation change, weather conditions, and your personal hiking speed.

No hiker, especially a beginner, should set off down the trail without enough water. The information in this article will help you ensure you pack a sufficient amount of water for your next adventure with all of these variables in mind.

How Much Water To Bring On A Hike

Trail Length And Terrain Type

The length of your chosen trail and the type of terrain you’ll be hiking on are the first and most crucial factors in determining the amount of water to bring.

For each mile you are planning to hike, you should plan to carry 0.5 liters of water. So, for an average 3-mile hike, you’ll need 1.5 liters of water. For longer hikes, such as a 10-mile trail, you will need approximately 5 liters of water.

Take Difficulty Into Account

If the trail is especially rocky, steep, exposed to the elements, or otherwise rated as more difficult, then you should plan on bringing more water than you would on an easier trail.

Calculating the amount of water to bring based on terrain type is tricky, because there are many factors to consider. Remember that it’s better to err on the side of caution and bring a spare 8 ounces if you’re hiking a more difficult trail than you’re used to.

On your hike, be sure to track how much water you’re drinking, and how much is leaving your body. Aim to replace any liquid lost through urination and sweat in order to maintain hydration. Additionally, it’s always a good idea to store extra water in your car for when you return from your hike.

Elevation Change

In higher elevations, the air is thinner and contains less oxygen. This means your body will have to work harder to get the same amount of oxygen and continue its normal processes. When you’re already exerting yourself, this stress on your body increases, and staying hydrated can help immensely.

For every 1,000 feet change in elevation, you should pack 1 extra liter of water. This is partially due to the extra time it will take you to hike to that elevation, as well as to help your body maintain normal processes.

Weather Conditions

In normal hiking conditions, you should consume about 8 ounces (1 cup) every 30 minutes, but hiking in inclement weather increases the amount of water needed to stay hydrated.

When physically exerting yourself in the heat, the CDC recommends drinking 8 ounces of water every 15-20 minutes. Additionally, you should drink small amounts of water over several short intervals. This ensures your body is taking in the water properly without shocking your system.

In the extreme cold, it is just as important to drink water. It may not be obvious while hiking in freezing temperatures, but you do tend to sweat even when it’s cold. In order to help your body maintain heat and prevent hypothermia, you should drink the same amount of water in the extreme cold as you do in extreme heat.

Personal Hiking Speed

For those that hike at average speeds or faster (2-3+ miles per hour), it’s perfectly fine to use the recommended water consumption of 0.5 liters per mile. Slower hikers should plan their water by time spent outside, rather than by the mile. In this case, you should bring 0.5 liters for each hour you plan to be out.

How To Calculate How Much Water To Bring On A Hike

Now that you’re an expert on knowing what conditions will require more water, let’s bring it all together in an example. Let’s say you’re going on a 5-mile day hike. You’ve researched the trail, as any good hiker would, and you found that you’ll be hiking mostly on a rocky slope with a total elevation gain of approximately 400 feet.

You’re an average hiker, covering around 2 miles per hour, but because of the change in elevation you know it may take a little longer to summit. You’ve also diligently checked the weather report and found that it should be relatively normal conditions during your hike, with the possibility of getting warm in the afternoon, but nothing too extreme.

To complete your 5-mile hike, you’ll need a minimum of 2.5 liters of water. Based on the elevation gain calculation of 1 extra liter for every 1,000 feet, you want to pack another 0.4 liters. Since you know there is a chance it will be warm on the trail, you decide to round this extra water up from 0.4 to 0.5 liters.

This brings your total to 3 liters of water for your moderately difficult 5-mile hike. Since each liter of water weighs a little over 2 pounds, the question then becomes: how will you carry all this water on your hike?

How To Carry Water While Hiking

Disposable Water Bottles

Although I’ve seen it on the trail many times, lugging out multiple small (16 oz) disposable water bottles for your hike is not the way to go. These tend to produce a lot of waste that is too easy to get left behind. For responsible hikers that do pack it out, single-use bottles are bulky and take up a lot of space in your pack.

Instead, many experienced hikers swear by using one extra-large disposable bottle, because they are lightweight, easy to drink from on the trail and can be refilled at home for your next hike. The largest of these bottles carries about 1-1.5 liters of water, optimal for a 2-3 hour hike.

Reusable Water Bottles

Instead of disposables, invest in a large reusable water bottle. There are many on the market to choose from that range in price and size, but I recommend at least a 48 oz bottle for hiking. This will allow you to carry approximately 1.5 liters with you, enough for a 3-mile day hike in average conditions.

I recommend getting a 48 oz Nalgene bottle for day hiking. These BPA-free plastic reusable water bottles are fairly popular because they are inexpensive and lightweight, while carrying a large amount of water.

If you prefer ice-cold water on the trail and don’t mind a bit of extra weight or expense, a Hydroflask is the way to go! The double-wall insulation of these bottles will keep ice in your water for a full day, even in the heat.

Hydration Packs

The most efficient way to carry large amounts of water while hiking is through the use of a hydration pack. These are essentially large sacks that will allow you to carry the water in your pack and easily access it through a long straw-like tube.

You can easily find a variety of hydration packs that hold 2-3 liters of water, which is ideal for longer hikes. These are available in a wide range of prices at almost all outdoor sporting goods stores like REI, as well as online marketplaces such as Amazon.

Consume Water Before, During And After Hiking

To maintain hydration long-term, it’s important to consume plenty of water before, during, and after exerting yourself. Before you pack out, drink at least 8-16 ounces (1-2 cups) of water.

Now that you’ve calculated how much water you need to bring, filled your water bottle or hydration pack, and are setting off down the trail, it hopefully goes without saying that now is the time to actually drink the water you’ve packed.

Be sure you drink small amounts of water throughout your hike, rather than downing it all at once to meet your liters-per-mile quota. If you’re worried about running out of water on your hike, just remember that the water you have does more good in your body than in your bottle. So drink up!

If you do run out of water and have no way to refill, it’s time to head back to the trailhead and make use of the spare full water bottle in your car. You should always plan to drink another 8-16 ounces of water after your hike to recover.

Final Thoughts

You should bring at least 0.5 liters of water for every mile of your planned hike. You should increase this if you’re planning to hike in hot weather, and if there will be a large elevation change. Also take into account your hiking speed, and the type of terrain.