Can You Go Hiking Without Water? (Know the Guidelines)
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Imagine, it is a hot summer day. Temperatures are sweltering and humidity is hovering over 90%. You planned a short two-mile hike with 500 feet of elevation gain in total. A moderately easy hike. However, you start to feel fatigued halfway through the hike and start to become dizzy. At this point, a number of things can go wrong and this is why you should have water at the ready.
You should always go hiking with at least a bottle of water. Even on the shortest and easiest of trails, you should bring at least a bottle of water with you as you will need at least 2 cups per hour of hiking. Dehydration can lead to performance issues and faulty decisions.
How Long Can You Hike Without Water?
If you are wondering how long you can hike without water we first need to discuss how long a human can survive without water in general. A human can last weeks without food but Science tells us that humans can only last up to 3 days without water in moderate conditions. Moderate conditions mean very little movement and minimum exposure to heat and humidity. If you are in a hot climate you will sweat more often and drain your body of the water and nutrients you desperately need. Thus, in warm climates, your intake of water needs to be more frequent. If you are hiking in a warm climate you are physically exerting yourself in conditions that will cause you to lose water at an accelerated rate.
There is no set time for how long you can hike without water but hiking all day without a sip of water will put you in serious jeopardy of succumbing to the elements sooner than the 3-day mark. According to the CDC, a total of more than 11,000 Americans have died from heat-related causes since 1979, according to death certificates. To note, there were almost 1,000 deaths in 2021.
How Much Water Do You Need to Take Hiking?
Trying to calculate the amount of water you will need for your hike will depend on the length of the hike, the difficulty of the terrain, the altitude, the temperature, overall pace and level of exertion, and some physiological factors.
Length of the hike - Depending on the miles/kilometers you plan to hike, just know that the average hiker moves at a pace of 2 miles per hour (3.2 kilometers/hour). If you are hiking a 4-mile trail it will take about 2 hours to complete. And if you need two cups of water for every hour of hiking you will need to consume at least 4 cups (or almost a liter) of water to stay hydrated.
The difficulty of the terrain - Our post “How Long Should a Day Hike Be?” outlines how to calculate the degree of difficulty for a hike. If you are traversing a harder trail then plan to bring extra water especially if your level of exertion will be normal-paced without breaks.
Altitude - If you are hiking somewhere where you are already thousands of feet above sea level be mindful that your body will need more water to stay hydrated, especially if you are not accustomed to high altitude traversing. You should plan to drink twice as much water at higher altitudes to keep hydrated. Staying hydrated also wards off altitude sickness which I have experienced firsthand a couple of times. Trust me, it is an awful feeling and the only cure I have found is consuming copious amounts of water.
Temperature - When the weather is hot you are prone to losing fluids at an accelerated rate. Per the Mayo Clinic, When it's hot and humid, your risk of dehydration and heat illness increases. That's because when the air is humid, sweat can't evaporate and cool you as quickly as it normally does, and this can lead to an increased body temperature and the need for more fluids.
Overall pace/level of exertion - If you maintain a fast pace and do not give your body a chance to cool, you will sweat more than normal and thus, need to increase your level of fluid intake. Take breaks when necessary and be careful not to over-exert yourself.
Physiological factors - In terms of sex, men will typically require more water than women. However, every person is unique and some women may require more water than men to stay hydrated. In fact, in a study conducted by the Mayo Clinic, you should take your weight and divide it by 2 to get the total number of ounces you should consume on a normal day.
Before we review the table below I want to advise that it might be wise to drink plenty of fluids right before you start the hike. This will ensure your body is fully hydrated and will help you start the hike on a strong hydrated foundation.
The table below is a rough guideline on how much water you might consume depending on distance and terrain. Again, every person is different and you may not require this exact amount. A very strenuous hike in high heat will require ample amounts (up to double the baseline requirement) of water intake. A lot of resources state that about one liter of water is required per hour on very strenuous hikes in hot weather. This will of course vary on the number of breaks you take to let your body cool.
What Should You Do If You Run Out of Water?
Always ensure you will be hiking near a water source. If not, again, plan for at least a half-liter (slightly over two cups) of water consumption per hour. A lot of hikers will carry at least a bottle or hydration pack and some form of water purification.
Water Purification systems are great. They allow you to carry less water (water is heavy - 2 cups is 1 pound) as you can use these systems when you come along a water source rather than carrying ALL the water you need for a hike. Here are some great water purification systems that will prevent you from ever running out of water (provided you where to find the water sources):