How Much Water Should I Drink a Day?

Water is an important part of every living thing in the world, from the smallest plants to the largest mammal, particularly for humans.

But how much water do you really need in a day? This article will discuss how much water is recommended per day, what happens if you don’t get enough water, and tips on how to get enough water if you’re not much of a drinker.

General Fluid Intake Recommendations

There are a number of different rules about how much water you need to drink in a day, and the most popular rule is the eight cups of water a day, equal to sixty-four ounces or a half of gallon.

1. 8 Glasses A Day

While sixty-four ounces of water is a significant amount of water, it is not a good rule to follow, as a number of different factors play a role in how much water you should be consuming in a day. Water consumption is not a one size fits all need. (1)

2. 9/13 Cups

Another common rule bases the amount of water on your gender. Women should aim to drink nine cups of water per day, while men should shoot for thirteen cups of water per day. The idea behind this is based on the fact that men are generally taller and heavier than women, meaning there is more body mass to hydrate. However, this again does not take into account other factors that play a role in water consumption. (2)

3. The 2/3 Rule

The ⅔ rule takes into account your weight when determining how much water you should be consuming daily. To find out the amount of water you should be consuming, multiply your current weight by .66. For example, if you weigh one hundred and fifty pounds pounds, you should aim to drink one hundred ounces of water per day. This method is a better way to hit an adequate amount of water as it is much less general than some of the other rules. (3)

4. The Gallon Rule

The gallon rule is exactly how it sounds: drink one hundred twenty-eight ounces of water every day. For many people, the gallon rule is a great way to be adequately hydrated. However, for others, a gallon of water is simply unnecessary, particularly those who are more inactive or have a smaller body mass than average. (4)

5. 2,200/3,000ml

What may be the best rule for water consumption is to drink until you are no longer thirsty, aiming to drink at least 2,200ml of water per day for women, and 3,000ml of water per day for men. (5) Continue to drink if you are still thirty. This doesn’t assume certain weights for men versus women, diet, activity levels, or other factors that can mean you need to drink more water throughout the course of the day.

How Do I Know If I Am Getting Enough Water?

Whatever rule you go by to make sure you get enough water, a couple of good ways to make sure you are getting enough water are as follows:


1. Urine Color

One of the best ways to determine if you are getting enough water, take a peak in the toilet the next time you use the bathroom. Ideally, your urine should be a very pale yellow, but not completely indistinguishable from the toilet water. You may be consuming too much water if your urine is completely invisible. This infographic can help explain what healthy urine looks like.

2. Feelings of Thirst

As discussed above, a good way to tell if you are getting enough water throughout the day is if you are feeling thirsty. If you drank enough water throughout the day, ideally you would go to bed not feeling thirsty. However, this can be a more difficult symptom to gauge, as those who haven’t been drinking enough water often find themselves confusing feeling of thirst with the feeling of hunger.

Additionally, various health concerns, such as diabetes and medication side effects, can make you feel thirsty no matter how much water you are drinking every day.

What Happens If I Don’t Drink Enough Water Each Day?

Drinking enough water everyday is incredibly important, as an adult human is composed of around seventy percent water. If you are not consuming enough water on a daily basis, you may find yourself with one or more of the following:


Dehydration may be the most concerning problem that you notice as a result of not drinking enough water. Mild dehydration can result in symptoms such as diarrhea, confusion, extreme thirst, and fatigue.

Mild dehydration can often be remedied through reducing physical activity and drinking plenty of water and sports drinks to help replace lost electrolytes and sodium.

More severe dehydration is marked by diarrhea lasting more than a day, drastically reduced or no urine production, bloody stools, and such extreme fatigue and confusion that day to day activities are affected. If anyone is experiencing this level of dehydration, a trip to the doctor or emergency room is in order. (6)

2. Digestive Issues

While dehydration can lead to diarrhea, a regular lack of water can lead to other digestive issues as well. Water is important for the digestive system to function optimally because it helps move waste through the intestines.

As the waste moves through the digestive system, excess water is absorbed through the walls of the intestines. If there is not enough water, the waste becomes hard and becomes difficult to move, resulting in constipation. (7)

Chronic constipation can lead to the development of hemorrhoids, which are painful, swollen veins in the rectum and anus that result from straining to defecate. Constipation also goes hand in hand with anal fissures, tiny tears in the delicate tissue. (8)

3. Decreased Immune System Response and Detoxification

Water is also incredibly important for maintaining a healthy immune system. Without enough water, the kidneys are not able to function properly and filter toxins out of the body. Water also helps the body to produce lymph, a substance created in the lymph nodes that helps flush toxins out of various systems.

Lack of water can also contribute to complications with arthritis, as water is needed to keep joints lubricated, as well as an increased risk of depression, as the water is needed in order for the brain to produce serotonin. (9)

4. Difficulty Losing Weight

Nearly two-thirds of American adults struggle with their weight and are considered to be obese or overweight. Not getting enough water is one thing that gets in the way of weight loss for a couple of different reasons. Water helps to keep your metabolism running smoothly, and if you are properly hydrated, it is harder to overeat. (10)

Tips to Help Increase Your Water Intake

Drinking enough water throughout the day can be difficult, particularly if you are not used to drinking large amounts or have been chugging sugary soft drinks or other less than healthy options.

1. Cut out other beverages.

The first tip is to cut out other drinks as much as possible. If you are drinking caffeinated coffee or soda, it may be difficult to remove these drinks completely, but cutting down on these sugary and unhealthy drinks will help you to drink enough water throughout the day. You may be surprised how easy it is to get enough water when that is all you are using to quench your thirst throughout the day.

2. Flavor your water with fruits, vegetables, spices and herbs.

You can flavor your water with fruits and vegetables such as lemons, strawberries, and cucumbers and herbs such as basil and mint to add some kick to your water to and give a healthy substitute for soda and overly sugary and processed juices.

3. Bring a water bottle with you.

Bringing a large water bottle along with you throughout your day will not only remind you to drink but also take away any excuses you have for not drinking. Many people also find it handy to tally water intake in their planner or calendar, and there are applications on your phone that will also help you keep track of your intake. (11)

Is It Possible To Drink Too Much Water?

While it is incredibly rare, it is possible to drink too much water. This condition, known as water intoxication or hyponatremia, occurs when an excessive amount of water is consumed more quickly than the body is able to sweat or urinate out, which in turn lowers the levels of sodium and electrolytes to dangerous levels.

This is a condition that is generally very easy to prevent by not exercising on extremely hot days, rehydrating after an intense workout with sports drinks that have electrolytes added, and not drinking more than a sixteen ounces of water in an hour. It is also fairly difficult to drink such an excessive amount of water, as the body will start to resist more water and the gag reflex will kick in.

When left untreated, this condition can lead to seizures, comas, and even death, so while it is very rare, it is very important to avoid and promptly treat this condition. (12)


Water is incredibly important for all parts of the human body, but many experts believe that most adults in the United States aren’t optimally hydrated.

While the amount of water you need every day is very dependent on how much you weigh, your activity level, the food you are eating, the climate you are living in, and any sort of medications or supplements you are taking, as well as various other factors, the most important thing is to listen to your body’s needs and be smart about your water consumption.

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