Dehydration is a common cause of many ailments that bring patients to the ER daily. This includes headaches, dizziness, fatigue, nausea, abdominal cramping and constipation, muscle aches, and kidney stones. Biologically, this makes sense, given that 60% of our body is water.
The benefits of adequate hydration are undisputed.
So it’s no surprise that TikTok and social media abound with fads surrounding adequate hydration and hacks on achieving it. One of the more well-known is the #gallonofwateraday, encouraging participants to drink one gallon, or 4.5 liters, of water per day. Meanwhile, #cirkul has garnered almost 400 million views on TikTok for a seemingly normal-looking water bottle with an intensity-adjustable water-flavoring mechanism to stimulate drinking. And elsewhere on social media, Khloe Kardashian swears by her $23 motivational water bottle, a best-seller on Amazon.
But how much water do we need to drink daily?
The U.S. National Academies of Sciences, Engineering, and Medicine determined that an adequate daily fluid intake is about 3.7 liters of fluids per day for men and 2.7 liters for women. This seems like a lot, but remember that about 20% of our daily fluid intake comes from food. Multiple foods are 85% water, which is a great source of hydration and other important vitamins, including cucumbers, tomatoes, watermelon, apples, and kale.
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So, after accommodating fluids obtained from food, the adage of aiming to drink about six to eight glasses of water a day (1.2-1.5 liters) is generally agreed upon and seems practical. Higher daily amounts are needed for athletes, those who live in hot or humid climates or at high altitudes, and those sick with fever, vomiting, or diarrhea.
The truth is, there’s no magic formula to quantify adequate hydration. A ballpark idea of how much water you need daily might be more palatable anyway for those who feel the daily grind of chasing a number is too anxiety-provoking. In addition, a better metric is hydrating based on observable signs that your body is telling you it has had enough water.
In the ER, we determine adequate hydration by measuring hourly urine output and the concentration of electrolytes in complicated urinalysis tests. A practical hack at home and on the go is to pay attention to your urine. Urine that is dark yellow and has a strong odor indicates inadequate hydration. If the urine is as clear as water and you go multiple times an hour, you are overly hydrated. The goal is urine that is pale yellow. Another easy way to check whether you’re hydrated is to pinch the skin on the lower part of your arm; if the skin snaps back right away, you are hydrated. Start drinking if the skin is slow to return to its resting state.
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It’s also important to remember to stagger your water intake throughout the day. Drinking too much over a short period will make you feel bloated and full. And try to avoid playing catch-up in the evening unless you want to be waking up to use the bathroom multiple times at night when you should be sleeping.
Another pro tip: Drink water with your meals. Water aids digestion, especially in the chewing and swallowing stages, and keeps stool soft and moving through the bowel. A common misconception is that drinking water dilutes digestive juices and impedes nutrient absorption. But that’s a myth to be debunked another day.
Michael Daignault is a board-certified ER doctor in Los Angeles. He studied global health at Georgetown University and has a medical degree from Ben-Gurion University. He completed his residency training in emergency medicine at Lincoln Medical Center in the South Bronx. He is also a former United States Peace Corps volunteer. Find him on Instagram @dr.daignault.
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