If you live in a desert climate or you’ve ever spent time out in the sun on a hot day, you are well aware of how refreshing a full glass of water can be. After all, the human body needs to be well hydrated to function properly. But what if there is no water immediately available? How long can you actually survive in the desert before you need to replenish?
On average, a person cannot survive longer than three to four days without drinking water. While there are factors that can shorten or lengthen this, survivability time in the desert is ultimately dependent on the severity of environmental conditions and the individual’s genetics.
Surviving in the desert is highly dependent on keeping yourself cool and hydrated. But like with most things, it’s better to be overprepared than underprepared, and knowing how long your body can go in extreme conditions without water can help you plan ahead. Below, we will cover how long you can survive in the desert without water and exactly what factors into your survivability.
Desert climates range from hot and dry to coastal; some deserts, like those in the Antarctic, are even cold. The one thing that they have in common is that they typically lack water. People, like these deserts, also vary in what they can handle, yet we all need water to live.
As a general rule of thumb, the average person can survive without water for about three days. However, this doesn’t take into consideration each individual’s metabolic rate and the environmental conditions they are experiencing.
How long a person can survive without water is generally dependent on several factors, including heat, humidity, and how quickly water is leaving the body. Under ideal conditions, you may be able to survive over a week with limited or no water. However, conditions in the desert are hardly ideal.
Drinking water regularly keeps cells healthy and allows the body to function properly. When a person loses water rapidly, the body responds by slowing certain functions to conserve water.
During this process, a person may experience things like:
- Confusion and dizziness
- Joint and muscle stiffness
- Brain swelling
- Changes in blood pressure
Dehydration can eventually lead to shock and unresponsiveness if not treated. If you are in warm temperatures, your body will also have a hard time cooling down due to the lack of sweat from dehydration, which will put you at higher risk for heat stress, heat exhaustion, or heat stroke. Depending on how your body responds to heat, the severity of these effects could happen in as little as a few hours.
It’s important to understand how the body is losing water if you want to know how long you will survive in the desert without the ability to rehydrate. Urination is usually the first thing that comes to mind thinking about water leaving the body. However, water exits the body in many ways, including sweat and in the air we exhale.
Desert temperatures can reach considerably high levels. This can be dangerous for your health as our bodies are designed to stay at a certain temperature. In order to help you cool off, your body uses water to produce sweat, which, in turn, depletes your water levels. Without water, the body cannot function correctly and will begin to shut down.
Dehydration can hit the body quickly—especially in extremely hot conditions—leading to a drop in blood volume, dry mouth, confusion, fatigue, and much more. Eventually, you will become unresponsive if you cannot replenish your water.
But how do you know how you will hold up in the desert?
Metabolic Rate and Genetics Determine Water Loss
There are several factors that determine how much water a person needs. Age, sex, activity level, and overall health will change the amount of water a person needs to take in to reach optimal hydration. These also determine how quickly you lose water.
The average person loses about one liter of water per hour of exercise. Under extreme heat, that number can rise to up to 4 liters of sweat an hour. Losing that much sweat while working out at the gym or jogging around the neighborhood isn’t typically a problem, especially if you’re replenishing afterward. However, if that lost water is not replaced, the total volume of body fluid can fall quickly, and blood volume may drop as well.
Climate Conditions in the Desert
Climate conditions also play a major role in how quickly water leaves the body. Whether the temperature is hot or cold, spending extended time in an arid atmosphere can quickly dehydrate you.
While heat can cause your body to lose water from sweat, extreme cold can see an increase in fluid loss as well. Sweat evaporates more quickly in cold air, and more fluids are also lost through water vapor in your breath.
The preparations you take can change based on the climate you are in, so it’s a good idea to understand the desert climate type you will be in. Here’s a brief rundown of different desert climates:
- Hot and Dry Deserts: This is what most people think of when deserts are mentioned. These deserts are hot and dry year-round and reach some of the highest temperatures on the planet.
- Semi-arid Deserts: These deserts are a bit cooler on average, with long, dry summers. If you find yourself in a semi-arid desert during the colder months, you may be in luck as winters tend to see a bit of rainfall.
- Coastal Deserts: Though these deserts are near a water source, they are some of the driest deserts on the planet. This is because most of the precipitation occurs in the ocean, with very little amounts of moisture reaching land.
- Cold Deserts: While these deserts are much cooler than the other types, they are still extremely dry. On top of dehydration, hypothermia is more like to be a problem than heatstroke. Cold deserts are typically found in the Antarctic, though they can also be found in areas 3,000 feet above sea level.
In a climate that receives less than 10 inches of precipitation in a year, water is the most vital thing you can find in a desert, but it isn’t easy to come by. The ability to locate a water source could be the deciding factor in how long you can survive in the desert, but first, you need to know where to look.
Follow the Bees
Bees need water for temperature regulation and metabolic purposes, and they tend to have a preference for mineral heavy water. For this reason, honey bees are able to use their antenna to locate water. If you see a bee, follow it; it may just lead you straight to a water source.
Flies and mosquitos are also a good sign that water is nearby.
Listen to the Birds
Just like bees, following birds is can quickly lead you to a source of water. Listen for birdsong or watch the sky for circling raptors. This might give you an idea of which direction you should walk.
Dig for your Water
If you come across any green plants or damp ground, dig a few feet in the soil until it becomes moist. Then, wait for the water to seep into the hole. This won’t provide a lot, but it may hydrate you enough to survive until you are rescued.
Don’t Eat Cacti
We’ve all heard how birds drink water from a cactus in the desert, but that’s not the best idea for humans. Many cactus species protect themselves with acids and alkaloids that are taxing on our organs. While it might give you hydration at the moment, the vomiting and diarrhea ingesting a cactus can cause will surely hurt you in the long run.
Collect Morning Dew
While it’s not a good idea to eat the cacti, you can collect dew from them before dawn. Just dab an absorbent cloth over the plant and squeeze it into a container.
Check Lower Terrain
Remember, water flows down. If you are in a mountainous or hilly area, the base of these areas could be home to a source of water. Your best bet will be to check a north-facing canyon if you are in the Northern Hemisphere, as snow or rainfall is more likely to be retained in these shaded areas.
While water is essential for surviving in the desert, it’s not the only thing you need to worry about. If you find yourself lost in the desert, here are a few survival tips to keep in mind to keep you trekking until help arrives.
Keep Out of the Sun
Protecting yourself from the sun needs to be one of your top priorities when trying to survive in the desert. If you don’t have shelter available, do your best to cover your head with a hat or cloth. The longer your body is exposed to the sun, the harder it must work to keep itself cool.
At the hottest point of the day, it’s best to look for temporary shade to protect you from the sun’s dehydrating rays. Look for shade from large cacti or a rock outcropping. If you need to move, do so in the cooler hours of the morning and evening, and shelter up during the midday and night.
Don’t Eat your Food
If you have food but are lacking water, it is best to go hungry. Your body can survive much longer without food than it can without water. The more you eat, the thirstier you will become, as your digestive process uses water.
Limit How Much You Sweat
Sweat is going to be your worst enemy if you’re trying to conserve body moisture. Move slowly so that you aren’t overexerting yourself, and try to keep your body temperature at around 98 degrees Fahrenheit. Your best bet is to create a shaded shelter that will allow the breeze in and wait for the sun to cool off before moving around.
Breathe Through Your Nose
The vapors we expel when breathing can contribute heavily to water loss—especially out in the desert. To conserver the moisture in your body, keep your mouth closed and focus on breathing through your nose.
Keep Off the Ground
Stay off the ground if at all possible. The desert floor and reach upward of 30 degrees hotter than the air. If you’re exhausted and need to lie down, find a shaded area to rest or use any gear that you have to put at least a foot of space between you and the ground.
Stay Warm at Night
Though the desert sun may be scorching hot during the day, temperatures can drop to freezing at night. If you can, build a fire using sage and dry brush to stay warm. Some simple shelter will also go a long way in keeping your energy levels up.
Don’t Forget to Signal
If you have the right equipment, stay put and try signaling for help. If you told anyone where you were going (which you should ALWAYS do), help should be on the way. If you feel like you need to move, leave a trail of breadcrumbs using sticks or rocks pointing in the direction you are moving so that rescuers know where to look for you.
Water is essential for human life, and dehydration can happen faster than you think. While some may be able to survive without water for over a week, the harsh conditions of desert climates can greatly lower that survival time.
Surviving in the desert is hard enough on its own; you don’t need the lack of water to make things worse. Whether you live in the desert or plan on taking a weekend trip, make sure to take extra precautions. It’s better to plan ahead than have to adapt to the moment. Pack more water than you think you’ll need, bring items that will help you keep cool, and always have a backup plan in case of emergencies.