How much water should you drink per day?

Everyone knows it’s important to make sure you’re drinking enough water in order to stay healthy. But knowing exactly how much water you need to drink each day can be tricky.

The human body is about 50 to 60% water. Every cell, tissue and organ in your body needs water to work properly. Water is needed for things like proper digestion and transportation of nutrients, lubrication of joints, circulation, saliva and maintenance of body temperature.

How much water should you drink each day?

Every day, you lose water through your breath, perspiration, urine and bowel movements. For your body to function properly, you must replenish its water supply by consuming beverages and foods that contain water.

Considering that even mild dehydration can make you feel tired and sluggish, it’s important to get enough water each day. There are many factors that can affect how much fluid a person needs, including gender, weight and medical conditions. According to the National Academy of Sciences, women need an average of about 2.7 liters (91 ounces) of water and men need an average of about 3.7 liters (125 ounces) per day.

Hot weather, exercise and even pregnancy can increase the amount of fluid a person needs to consume each day. A doctor or registered dietitian can help you determine the amount of water that's right for you.

Is it possible to drink too much water?

While it’s very rare, it is possible to drink too much water, which can then cause low sodium levels and lead to hyponatremia.

Hyponatremia is caused by drinking too much fluid, which dilutes blood salt levels below the normal range. Any sudden drop in blood salt levels caused by drinking more than the body can excrete can cause all cells in the body to swell. Brain swelling from hyponatremia can cause headaches and vomiting, while muscle cell swelling can trigger whole-body muscle cramping. This typically occurs if you drink excessive amounts of water in a very short amount of time, like drinking a few gallons of water over an hour or two.

Sometimes when overhydration occurs, only mild symptoms like distractibility occur. If more serious or rapid overhydration occurs, vomiting and trouble keeping balance can develop. Eventually, people can experience confusion, seizures or swelling in the legs caused by fluid accumulation.

Athletes — especially if they participate in long or intense workouts or endurance events — are at higher risk of hyponatremia. In general, though, drinking too much water is rare in healthy adults who eat an average American diet.

What’s a good way to determine your hydration levels?

Urine can be a good way to gauge hydration status. It’s normal to have pale yellow urine. If it’s honey or amber colored, that can suggest that you need to drink more fluids.

It’s important to remember that some medications can affect urine color, but dark orange or brown urine may be a sign of other medical conditions that you should discuss with your doctor.