Is drinking too much water bad for you?

Water is the basis of life. The human body is made up of up to 60% of water because every cell needs it to function properly. Drinking adequate amounts of water helps the body regulate temperature, prevent constipation, flush out waste products, and perform all major bodily functions. While most people are concerned about not drinking enough water, drinking too much water can be as dangerous as a poison and can have many harmful side effects.

There are two main types of overhydration: increased water intake and retention of water. An increased water intake occurs when there is more water consumed than the kidneys can remove. Our kidneys filter out excess waste and water from the bloodstream at 800-1000 mL of water per hour. If more water is consumed in an hour than the kidney can filter, the excess will seep out into the cells. Furthermore, the retention of water occurs when the body cannot get rid of water properly due to medical conditions such as heart disease and diabetes. When overhydration occurs, the water dilutes sodium levels, causing sodium levels to drop dangerously low, and interfere with organ functions. Sodium is an electrolyte that regulates how much water goes in and out of cells, and when it decreases too quickly in the human body, it can become fatal. 

Overhydration can cause nausea, confusion, headaches, drowsiness, muscle cramps, and in extreme cases, seizures and comas. When overhydration is diagnosed, the treatment depends on the cause and severity of symptoms. Treatments may include cutting back on your fluid intake, taking diuretics to increase the amount of urine you produce, treating the condition that caused the overhydration, stopping any medications causing the problem, and in severe cases, replacing sodium. 

While most doctors advise that every person should drink 8 glasses of water per day, this number can fluctuate based on exercise, environment, weight, and sex. On average, the U.S. National Academies of Sciences, Engineering, and Medicine determined that an adequate daily fluid intake is about 15.5 cups of fluids a day for men and 11.5 cups of fluids a day for women, which would further vary based on the other factors. To prevent dehydration and overhydration, drink water with each meal and between meals, before and during exercise, and when you feel thirsty. You are drinking enough and not too much water when you rarely feel thirsty and your urine is colorless or light yellow.

Nevertheless, drinking too much water isn’t always connected to thirst. Some athletes, especially those in an endurance sport like long-distance running or biking, are prone to accidental overhydration. Because dehydration negatively affects their performance, they often tend to over-prepare by drinking too much water. In other cases, dieters will drink excessive amounts of water because it takes up space in the stomach, staving off their cravings for food. 

While overhydration can be extremely fatal, it is also rare and occurs mostly in intense athletes. Therefore, it is difficult to accidentally drink too much water, as long as you stay roughly around 8 glasses per day.