How much water you should drink on a hike is a tricky question to answer because there are so many different factors that are involved in giving an accurate response. It requires a little bit of personal preference, a bit of science, and a lot to do with the environment that you will be hiking in. But in this article, I will break down how much water you should drink on a hike so that you’ll be adequately prepared.

Table of Contents

How much water you should drink normally?

Let’s start with how much water you should be drinking on a normal day-to-day basis, as that seems like it would be a good starting point.

You probably heard you should be drinking eight, eight-ounce glasses of water a day right? (The infamous “8×8 rule.”)

That comes out to 64 ounces or 1.89 liters.

But that number may be arbitrary, as “rigorous proof for this counsel appears to be lacking.

In fact, other sources claim you should be drinking much more water than that but it depends on your age group and sex.

For example, the Dietary Reference Intake from the Institute of Medicine offers guidelines for adequate water consumption for children and adults.

Adequate daily water intake by age:

Children ages 1 to 3: 1.3 L (44 oz.)
Children ages 4 to 8: 1.7 L (57 oz.)
Males ages 9 to 13: 2.4 L (81 oz.)
Males ages 14 to 18: 3.3 L (112 oz.)
Males ages 19 and older: 3.7 L (125 oz.)
Females ages 9 to 13: 2.1 L (71 oz.)
Females ages 14 to 18: 2.3 L (78 oz.)
Females ages 19 and older: 2.7 L (91 oz.)

So if you are a male in your 20s or older, you should be drinking about 0.21 liters per hour (assuming that you are awake about 17 hours per day).

Of course, that requirement is spread out through an entire day and when you’re hiking you are exerting yourself within a much tighter window so your drinking requirements per hour will go way up. So while these guidelines are informative, they’re not super helpful when it comes to planning water consumption for a hike.

It’s best to test out your personal water requirements on hikes of different difficulties and lengths. Start slow and work your way up and eventually you will have a good idea of how much water is required for you to remain comfortable throughout different types of hikes.

How much water should you drink when hiking?

Okay, so we don’t really have a universal baseline for all humans when it comes to how much water you need.

But that doesn’t mean that you can’t find guidelines out there from others based on prior experience.

One guideline I’ve seen a lot is drinking 1L of water for every two hours when hiking.

In my hiking experience, this is pretty on point, especially when hiking in mild to cool conditions.

But it does not apply when hiking in high temperatures such as in the desert during the summer.

When hiking in the heat of the summer, you should shoot for something closer to 1L for every hour, as recommended by the National Park Service.

If you’re hiking at high altitude, dehydration can sneak up on you since your “thirst triggers” may not be firing away due to colder temperatures and you might be subject to more frequent urination as you adjust to the altitude.

Also, According to the Wilderness Medical Society, you lose water through respiration at high altitude twice as quickly as you do at sea level.

So increased water consumption above 1L of water for every two hours may be needed.

The Institute for Altitude Medicine, states to plan to drink an extra 1 to 1.5 liters of water daily when at high altitudes. If you’re going to be higher than 10,000 feet, the Wilderness Medical Society recommends drinking a total of 3 to 4 liters daily of liquids (along with 200 to 300 grams of carbohydrates).

If you are doing longer hikes then things are a little bit different as you want to be focused on the total amount of water per day. For example, the National Park Service states that if you’re hiking in the Grand Canyon you should be drinking 4 liters of water per day.

Keep in mind that the more consecutive days that you hike, the more your dehydration may be cumulative. At a certain point, you may not be able to safely drink enough water to make up for the past few days of dehydration so that’s why it is very important to steadily drink water throughout your journey.

And finally, the terrain and level of effort required to get through the terrain is a huge factor as well. A flat stroll for 4 miles is a completely different animal from a 4 mile out and back scramble. Pay attention to elevation gain, grade, and the nature of the trail/route so you can plan your water supply correctly.

Don’t drink too much water

The other thing you need to think about is regularly consuming smaller amounts of water rather than downing a huge amount of water in a short amount of time.

Personally, chugging water, or simply drinking water voraciously within a short amount of time, when exerting myself heavily in heat makes me feel sick but more importantly your body can only absorb so much water per hour.

The National Park Service states:

During the summer months, your fluid/electrolyte loss can exceed two quarts per hour if you hike uphill in direct sunlight during the hottest part of the day…. Your body can absorb only about one quart [32 fluid ounces] of fluid per hour. Drink one-half to one full quart of water or sports drink each and every hour you are hiking in the heat.

So sipping water throughout a hike is much more effective than chugging water and it will help you to prevent getting sick.

Water intoxication can be a threat if you drink too much H2O.

Too much water can dilute electrolytes in your blood and can lead to very low sodium levels — a condition called hyponatremia, which can be life-threatening.

Studies show that you usually have to drink very large quantities of water in short amounts of time for this to happen.

For example, one report describes how three soldiers died due to hyponatremia and cerebral edema and these deaths were associated with drinking 10 to 20 liters of water in only a few hours.

Here are some other data points for water toxicity:

Half a gallon of water (1.8 liters or more) per hour (Source).
2.5 to 5.6 gallons (10 to 20 liters) in just a few hours (Source)
1.5 gallons (6 liters) of water in 3 hours (Source).

So to avoid hyponatremia symptoms, you should not drink more than about 1.0 liters of water per hour, on average. Once you start approaching a couple of liters of water per hour then that is when things start to get a little bit risky.

But ultimately, you also need to listen to your thirst. As stated by Dr. David Geier, a sports medicine specialist, “For most athletes, the best hydration strategy before, during, and immediately following exercise is to drink fluids when thirsty.”

Electrolytes

Electrolytes are extremely important to maintaining proper fluid balance, muscular contraction, and nervous system function. And the last thing you want on a strenuous hike when up on a steep switchbacks is for you to be losing concentration or control of your muscles.

In addition to water, I make sure that I also have at least one Gatorade bottle with me on hikes. Sports drinks high in sodium, potassium, magnesium, and calcium can help retain fluids so they are great to supplement with your water supply.

Of course, you could also have some kind of electrolyte mix that you pour into your water or other beverage or get them from foods like:

spinach
kale
avocados
broccoli
potatoes
beans
almonds
peanuts
soybeans
tofu
strawberries
watermelon
oranges
bananas
tomatoes
milk
yogurt
turkey
chicken
raisins
olives

You can also make homemade electrolyte recipes.

How to stay hydrated when hiking

Pre-hiking hydration

The first step is to not get dehydrated before you ever begin your activities.

In the excitement of getting ready and traveling to the trailhead, it’s totally possible that you could forget to drink water that morning or even the night before leading you to already be borderline dehydrated before you ever start.

I make sure to start hydrating myself the night before a hike and then make an extra effort to drink additional water that morning. According to the American College of Sports Medicine, to avoid dehydration active people should drink at least 16 to 20 ounces of fluid one to two hours before an outdoor activity. (One bottle of water would fit this bill.)

Drink before you are thirsty

When you are out on the trails, be sure to drink water before you are thirsty because at that point dehydration is already setting in. This is one reason why water reservoirs are so great because you can quickly take a few sips without having to stop and pull water bottles from your backpack.

A 2L hydration pack is pretty good for a lot of short to medium day hikes but for much longer and strenuous hikes, you might want to look into a 3L+ pack. (Personally, I use the TETON Sports Oasis 1100 Hydration Pack).

Monitor your urine

Your urine can be a key way to measure whether or not you are dehydrated. You want your urine frequency, clarity, and volume to be as normal as possible.

You will know that you were not drinking enough water if your urine is dark, small in quantity, or perhaps even nonexistent.

Avoid the middle of the day

If you are a desert dweller like myself, then you know that water intake is extremely important if you are hiking in the middle of the day. Personally, I just try to avoid hiking in the heat of the day for hours when dealing with above 100º temperatures.

I usually set out around sunrise which allows me to knock out a few hours of hiking before temperatures shoot up. That would be my recommended way to go but if you have to hike under the brutal sun then make sure you are overestimating your water consumption. Again, one liter per hour is a good way to estimate your needs.

Be aware of water sources

Be on the lookout for water sources along your route. You might find creeks, rivers, or even springs and if you have some kind of filtering device like a LifeStraw, you can use that to help you stay hydrated.

I like relying on these methods because it allows you to have less weight in your pack but you need to be extra sure that those water sources will not be dried up, especially if you are hiking in the desert.

Utilize foods

Remember that foods can also have lots of water in them, such as fruits. Foods like watermelon, cucumbers, celery, and blackberries have high amounts of water in them. As mentioned, foods are also a great way to get electrolytes put back into your system.

Wear the right gear

Exposing yourself to the sun will lead to dehydration quicker. I’ve noticed that I do much better with respect to dehydration when I am wearing proper hiking attire. The most essential items for me are sunscreen, UPF long-sleeve shirts, and a wide-brimmed UPF hat.

It’s also important to have gear that is very breathable so that you can sweat and that sweat can be easily evaporated, allowing your body to cool.

Head back when needed

Also, an important thing to remember is that once you get halfway through the water supply, you should be prepared to turn around on your hike.

Rehydrate when finished

Always try to have water and water fluids available once you finish a hike, as this will assist with recovery. You can think about at least drinking one glass of water when you finish but some recommend drinking 16 to 24 fluid ounces for every pound that you lost when hiking.

Final word

So in conclusion, you can drink about half a liter per hour on normal hikes and closer to 1L per hour in very hot environments. You don’t want to drink a lot more than 1L per hour on average because you could risk drinking too much water and get sick.

You also want to consume electrolytes and to consider other ways that you can mitigate the risk of dehydration with proper planning and gear.

If you do all of those things then you should be good to go!

How Much Water Should You Drink on a Hike?