TL;DR - Plan to drink 0.5 - 1 liter of water for every hour of hiking.
No matter the length of the hike, being hydrated is important. Thus, one of the essential items to pack is water.
While knowing you should bring water seems like a simple concept, if you are new to hiking or taking on longer mileage, knowing how much water to bring takes a bit more thought.
Additionally, if you are spending multiple days out in the wilderness, you likely won't be able to carry all of the water you'll need. When you overlook these seemingly small details, they could have dire consequences.
Luckily, there are a few simple ways to figure out how much water you need to bring hiking. All it takes is some preparation and know-how.
Here is what you will learn in this article:
Staying Hydrated Basics
Before you can decide how much water you'll need for the hike, ask yourself a few questions:
- How long will you be hiking?
- What are the weather conditions?
- What is your elevation?
- How much water do you drink regularly?
These four questions will help you personalize the standard calculations we will describe in the next section.
The distance and temperature will be the two most important factors.
If you are hiking in a hot, high desert environment, you may need to be hydrated more than if you are hiking on a crisp Autumn day.
How Much Water to Bring Hiking
Instead of basing the amount of water off how many miles you hike, a safer way to calculate is by how long it will take you to hike that distance.
Things like terrain, your physical conditioning, and if you are hiking with children can all make a somewhat short 2-mile hike into a multi-hour adventure.
For every one hour of hiking, the average adult should drink 0.5 - 1 liter of water.
For children, depending on their age, anywhere from .25 - 0.5 liters of water per hour will be enough.
Other than age, determining how much you will drink within that range will depend on your hiking pace, temperature, and terrain.
For instance, if you are hiking on a hot summer day on strenuous terrain, you're more likely to want to drink around 1 liter of water.
If you walk at an average pace, the activity level is moderate, 0.5 liters of water could be okay.
As you begin to make hiking a part of your life, you will get to know how much water you drink on average.
If you're unsure, though, the guidance above is a good starting point. After all, it is better to over-prepare than under-prepare.
Before you even leave for your hike, remember to be hydrated as well.
Try to drink around 17-20 fl oz 2 hours before you plan to start hiking.
Then, as you hike, remember to sip, don't chug—plan to drink some water every 10-15 minutes as you're exploring the trail.
If you tend to forget to hydrate while exploring, a good tip is to set an alarm to remind you to take a sip. See our Best Picks for Hiking Watches.
Our bodies can only process 1 liter of water per hour, and if we are chugging all of that at once, it passes through our system too quickly and isn't as effective in hydrating.
Pro Tip: Remember to wear sunblock. Sunburn can increase dehydration.
You'll also want to start the habit of re-hydrating after you've finished your hike.
Pro Tip: Add electrolytes to your water to replenish what you lose through sweat and exertion.
A great electrolyte product we like is the Nuun Sport range. It's a tablet that you simply add to your water bottle or hydration bladder.
How Much Water to Bring Backpacking
These calculations become more complicated when you move from a day hike to backpacking, though.
When you're backpacking for four days, you won't be carrying water for all four days.
You'll still be able to apply the same concept as above, but you'll also have to factor in water access on the trail and water purification and filtration. To learn more about the options, check out our guide to the Best Water Purifiers.
Beyond factoring in how much water you're bringing, you'll need to think about how much that water weighs. So, if on the first day of this backpacking trip, you plan to hike 6 miles.
First, determine how long you think it will take you to walk that distance. Let's say it takes 30 minutes to hike one mile.
- 6 miles at 30 minutes per mile = 3 hours
Now, that is a pretty brisk pace, especially when backpacking. So, we will also need to factor in terrain changes and breaks along the way. With all of that, let's round it up to 4 hours.
- 6 miles of hiking = 4 hours = 2-4 liters of water
- 1 liter of water = 2.2 lbs (1 kilogram)
- 2-4 liters of water = 4.4-8.8 lbs (2-4 kilograms)
Since we are backpacking in this example, it is crucial to recognize that you will need to use water beyond staying hydrated. You'll need water for cooking as well.
Plus, you will need water for that night to drink and in the morning before you start the next day.
The good news is that depending on where you are backpacking, you likely won't have to carry the entire 8+ lbs of water as you trek.
Find out if there are water sources along the way, and if there is, you can stop throughout the hike to refill.
Keep in mind that you'll need to properly filter and purify the water you collect on the trail. If you have frequent access to water, you can easily choose to carry only 1-2 liters of water with little worry.
How to Carry Water When Hiking
Once you've determined how much water you need to pack to hike that day, you will also need a way to carry it. The best way to stay hydrated is to have your water be easily accessible.
If the water is difficult to access, it is much easier to forget to drink or not want to because you'll have to stop hiking.
The two most common containers to carry water while hiking include:
- Water bottle
- Hydration bladder
Water bottles are one of the most common containers for water. They are affordable and durable, but they do tend to be heavier and bulkier to pack.
Water bottles tend to have hard sides, and they are relatively easy to drink from and carry. Some of the best water bottles for hiking include are made by Nalgene. We also recommend the collapsible Platypus Bottle.
A water bladder is what you put in a hydration pack. You can pack a water bladder even if you don't have a hose hookup. This is an excellent way to carry large amounts of water that you can use to fill bottles.
If you do not have a hydration pack but want the extra water, we recommend an MSR Dromedary for its durability and numerous size options.
You can also hook up a hose to the MSR water bladders to use them inside a hydration pack. To find the right hydration bladder for your needs, check out our Best Hydration Bladder Buying Guide.
One of the most common hydration pack options is a Camelbak. Their packs come in various sizes as do their water bladders.
The nice thing about using a hydration pack is that you don't have to stop to get a drink. Thus staying hydrated is easy.
The downside is that they can be challenging to clean after a while, and they are easier to puncture.
How to Avoid Dehydration while Hiking
When it comes to dehydration, the best way to avoid it is to follow the tips we listed above.
Remember, if you are to the point of feeling thirsty, dehydration has already begun.
If you ignore this and continue without drinking water, you could start to experience these early signs of dehydration:
- Dry mouth
- Low energy
Continuing forward, if you continue to drink no water or very little water, your symptoms are likely to worsen.
Some of the most severe signs and symptoms of dehydration include:
- Muscle and stomach cramps
- Dark urine
- Stumbling or loss of coordination
- Mumbling or unclear speech
If you or a hiking partner has reached the point of vomiting or fainting due to dehydration, medical assistance is required.
How to Avoid Over-Hydration while Hiking
While we may be aware that dehydration can be an issue when hiking, over-hydration, also referred to as hyponatremia, is just as dangerous.
It may be far less common, but it is essential to be mindful that it is possible and poses serious safety risks.
The symptoms are far rarer to experience, and usually only occurs in long-distance athletes like ultra-marathon runners.
Mainly, what happens when you drink too much water is that your blood's sodium levels become so low that cell function is interrupted or impaired.
Unfortunately, many hyponatremia symptoms are very similar to dehydration, including headaches, fatigue, and nausea.
This overlap in symptoms can influence people to drink more water, making the issue far worse. In extreme cases, hyponatremia has caused comas or even death.
Both dehydration and overhydration are dangerous, but the good news is that they are entirely avoidable if you properly prepare.
Not only that, but it is vital to monitor and be aware of how much water you are drinking as you hike.
Staying hydrated on the trail is critical.
Before you go ask yourself these questions: How long will you be hiking? What are the weather conditions? What is your elevation? How much water do you drink regularly?
As a starting point, drink 0.5 - 1 liters of water every hour while hiking.
With some preparation and know-how you can avoid the dire consequences of dehydration.
Happy & Safe Hiking!
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