How long can a human go without water?

In this brief guide, we will answer the question, “how long can a human go without water?” and discuss what are the signs of dehydration, and why is drinking water so important?

How long can a human go without water?

Humans can go without water for around 3 days, but it depends on the person.

The human body relies on water to keep itself functioning properly, so if someone doesn’t drink enough water, their organs will start shutting down. The brain and heart are especially sensitive to dehydration, and they can go into cardiac arrest within hours of not drinking enough fluids. 

Drinking only small amounts of water over long periods of time can also lead to severe dehydration, which can cause dizziness, fainting spells, nausea, and vomiting.

The average adult should drink about six 8-ounce cups of fluid every day, which is equivalent to about two liters (about half a gallon or 64 ounces) of fluid every day. Because if you don’t get enough drinking water into your system, your kidneys will stop filtering waste products from your blood, and this can lead to kidney failure or anemia.

The human body is made up of about 70% water and needs to stay hydrated to function properly. Water is essential for the body’s proper functioning and can be stored in the body’s tissues and organs, such as the brain and lungs.

The average adult human can go without drinking water for 3 days before becoming dehydrated, though some people have been known to go longer than that. The body will draw on its reserves of carbohydrates, proteins, and fats if it doesn’t have enough water inside it. Without access to food or drink, the body uses those foods as energy sources while it begins to break down its own cells.

If you are severely dehydrated (your urine has a strong yellow color), even after 4 days without drinking water, you may need medical intervention or hospitalization. In these cases, doctors will give patients intravenous fluids by inserting an IV tube directly into a vein in their arm.

How does dehydration affect our brain?

Dehydration affects the brain in many ways:

The most noticeable way that dehydration affects your brain is through the disruption of normal brain activity. As dehydration worsens, it can affect how our brains work, disrupting our mood and our ability to think clearly.

Another way that dehydration affects your brain is by causing swelling in your hypothalamus gland, which controls your body temperature and makes you feel thirsty. This swelling can cause headaches and fatigue as well as interfere with memory and concentration.

How does dehydration affect us physically?

Dehydration can affect us physically in a number of ways.

Even mild dehydration can leave us feeling more tired and less able to perform physically, while severe dehydration can cause us to have trouble breathing.

The first stage of dehydration is thirst which kicks in when 2% of body weight is lost. In this stage, the body starts to have trouble absorbing water, which causes us to feel thirsty and sometimes nauseous. We may also start to notice that our urine is dark-colored or has a strong odor.

If we continue to lose fluid from our body, we enter a second stage called stage three of dehydration. In this stage, our blood volume decreases further, which causes our blood pressure to rise and our blood sugar level to drop. This can cause dizziness and fatigue as well as headaches and nausea.

If we continue to lose fluid from our body after this point, we enter the third stage. This final stage involves kidney failure. The kidneys are unable to filter toxins out of your body.

Why is water so important?

Drinking water is extremely important in our daily lives. It’s something we need to be able to survive, and it’s also something that helps us maintain the health of our body systems.

Our skin and joints are made up of collagen, which is a protein that holds our skin together and keeps our joints mobile. When we don’t drink enough water, our collagen begins to break down, leading to wrinkles and joint pain.

Water also helps regulate metabolism, which means that it keeps your body from burning energy faster than it can produce it. The result is that you’ll feel fuller longer after eating fewer calories. This can help you lose weight. Finally, water helps flush out toxins from your body.

What are the signs of dehydration?

Here are some signs that you may be dehydrated:

  1. Dry mouth/thirst with little or no urine output
  1. Dark-colored urine
  1. Decreased urine output
  1. Feeling tired and weak
  1. Muscle cramps


In this brief guide, we have addressed the question, “how long can a human go without water?” and discussed other questions related to the subject, such as what are the signs of dehydration, and why is drinking water so important?