How Much Water Should I Drink Each Day?

Water plays a large part in our lives and a large part of nearly every living thing on the planet. Water has many different characteristics that make it ideal for life. A high resistance to temperature change, the ability to dissolve many different compounds, electrolytes with high potassium, calcium, and sodium levels for energy production, and the polar bonds linking water molecules together are just some of these characteristics.

With nearly all of life requiring water in some capacity, it is easy to assume that humans also require water to function. We are up to 60 percent water, after all. Because we are larger multicellular organisms, water is constantly lost to the environment and as such, we need to be drinking water on a regular basis. You've heard the old eight glasses of water per day adage, but the truth is actually more complicated. Below are common questions surrounding the need for water including why you need water, how long you can survive without water, recommendations on daily fluid intake for overall wellness, and more. With this information, you can be better informed about your hydration needs and facilitate better health by ensuring your body and its cells stay nice and hydrated.

Why do you need water?

The need to drink water is a basic need of humans, but you may wonder to yourself why water is so important. There are hundreds of different reasons as to why you need water and the more you learn about the human body and its physiology, the more you realize the importance of water in nearly every organ or organ system.

Within the digestive system, water is necessary to allow for proper digestion of your food. Without water, you would most likely experience constipation and would have a difficult time going to the restroom and absorbing nutrients from your food.

Within the circulatory system, the blood contains upwards of 90% water. Water is considered the universal solvent and makes it an ideal liquid to assist with carrying molecules throughout the body. These dissolved molecules include oxygen, carbon dioxide, glucose, and more. Additionally, since water makes up a majority of the blood volume, it also plays a large role in contributing to healthy blood pressure. When water intake is low it can lead to a decrease in blood volume and decrease in blood pressure which can have negative side effects.

Within your central nervous system, there is a fluid called cerebrospinal fluid and it contains up to 99% water in addition to molecules that help nourish the neurons within your central nervous system. If you lack water consumption then you will not be able to support your central nervous system optimally.

Water is also a critical component of the synovial fluid found within joints. Synovial fluid contains a large percentage of water and this liquid helps to reduce friction across a joint. Similar to synovial fluid, shows another instance where water plays a key role in proper lubrication and reduction in friction.

The last and one of the most important aspects of water is that it is utilized in the transport of waste products out of the body. The kidneys take the byproduct of protein breakdown and remove them through urination. Without water, your kidneys have less available solvent to get rid of the byproducts leading to toxic levels of urea.

How long can you go without water?

The question of how long you can go without water has many different components that make it a difficult question to answer. Depending on your relative activity level, age, and sex, the amount of time you can go without water can drastically differ. A good way to think about how long you can go without water is to think about your inputs and outputs. Your body wants to stay in a state of water balance and to accomplish this your body will adjust its inputs and outputs accordingly.

Let's say that you went on a run, expended a lot of energy, and sweat outside. This exercise is more likely to cause you to need to consume more water to make up for water lost to the outside world. These actions would decrease the amount of time you could go without water. In general, it is thought that a person could survive three days without water. This figure could change depending on the factors described above.


Recommended water consumption bases on:

Recommendations for water consumption are highly variable and dependent on many different factors including weight, gender, activity level, climate, and more. Assessing each of these different recommendations can allow you to have a better idea of how much water you need to consume in a day.


As stated before, your body consists of a large percentage of water. The more that you weigh, the more water your body has. A quick and easy hack to help you get a ballpark insight into your recommended water intake is to take half of your weight in pounds and change the units to ounces. In the case of a 200 pound individual, it would be advised to drink roughly 100 ounces of water a day. While this may seem like a lot of water initially, eventually your body will become accustomed to the water intake and will ensure you are within healthy ranges for the amount of water.

Assigned gender at birth

Your assigned gender as a newborn also has a large impact on how much water you will need in a given day in the future. Based upon the mayo clinic, it is advised that men drink roughly 15.5 cups of water daily while women should drink about 11.5 cups daily. These recommendations also take into account the water taken in through food. This means that these goals are a good representation of how much water you should drink in a day. Some recommendations do not take into account the average amount of water consumed through solid foods, as a result the recommendations can seem inflated.

Activity level

Activity level is another factor that plays into the amount of water you may need to drink in a given day. Water helps whether you're working out with body weight or on machines, but stay away from caffeinated beverages that don't contribute to your daily water intake. You can hydrate while exercising with a water bottle or a sports medicine-approved sports drink. Physical activity not only works your body, but it also heats it up. The more energy expended, the more inadvertent heat produced. While heat is important, too much heat can result in harm to delicate body systems. As a response, your body intentionally releases water through pores in the skin. The water is then evaporated, but during the process of evaporation it cools down the surface of the skin.

One study aimed to observe the amount of water loss due to sweat and found that people can lose as much as 10 liters of water through sweat alone during physical exercise. This is a lot of water weight loss and is not a significantly apparent way to lose water. For this reason, it is incredibly important to maintain adequate water consumption when exercising. Upping your consumption from the baseline recommendation is advised.

To effectively fuel your training or exercise routine, it is important to hydrate effectively before and after your session. Showing up to your session without hydrating can decrease your performance, decrease your energy levels, and is ultimately detrimental.

Temperature outside

Another factor that is easily forgotten about is the effects of your environment on your need for water. On a hot summer day the sun is constantly beating down and the air around you is hot. After a few minutes, you’ll begin to sweat and start losing water simply by standing around. You can begin to sweat just as much as you may during a workout so if you find yourself in a hot climate, ensure you are getting enough fluids.

Another environment that could require you to drink more fluids is dry environments. When you enter a dry environment, you may notice that there is little to no condensation on the outside of a cold beverage. This is because there is very little water vapor in the air that can condense on the outside of the glass. Because of this low water vapor, it's easier for water to evaporate. If you find yourself in a dry environment, you may feel like you aren’t sweating. In reality, you are just evaporating fast enough where you do not notice that you need extra water.


Medications are another common reason you may need to alter your water consumption. Some medications can increase water retention while others can put you at risk for dehydration. Ensure that you read any and all labels to ensure that you are getting the right amount of hydration.

One commonly used prescription medication that can cause dehydration is the utilization of diuretics. Diuretics are utilized to help with constipation. To accomplish this, the diuretic increases the water concentration in the large intestines which can lead to increased water loss through excretion.

Not all medications and supplements have a significant impact on hydration within the body.


Staying hydrated is key to helping your body perform its day-to-day function at its best. From helping you swallow your morning MitoQ supplement, to ensuring you have nice hydrated skin, water is a large player in your overall health. Simply ensuring you are drinking enough water is an easy thing you can do that can have huge positive impacts.

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