You’ve probably heard that it’s important to drink enough water and that water is the healthiest beverage. While these things are true, you can drink too much water. Overhydration may cause health problems. So may dehydration – drinking too little.

Being well-hydrated

  • Being well-hydrated helps nutrients and oxygen travel through your body efficiently.
  • It aids digestion and helps you maintain healthy blood pressure levels.
  • It enables you to excrete waste from your body and to sweat, so that you don’t overheat on hot days.
  • Dehydration may cause dizziness or fatigue and contribute to heat exhaustion.

What is overhydration?

Drinking more than 3½ cups to 4 cups of water in an hour may lead to overhydration. It’s better to sip gradually throughout the day than to swig a pitcher of water quickly.

  • Overhydration causes an electrolyte imbalance. The high volume of water may dilute your body’s sodium (salt) levels, disrupting the way your body normally works.
  • Overhydration may lead to headaches and confusion.
  • You may feel nauseous or sleepy, and you may develop vision problems, muscle cramps or elevated blood pressure levels.
  • In rare cases, overhydration may cause breathing difficulties, seizures and even death.

How much is too much?

Gulping down a glass of water on a hot day or after a workout shouldn’t lead to overhydration. People rarely drink enough to become overhydrated. It’s more common among athletes who do intense workouts: They may overdo their water intake, trying to stay hydrated, or they may drink a significant amount in a short period.

Everyone has individualized hydration needs, but generally, women should drink 9 cups of water daily, and men should drink 13 cups, according to the National Academy of Medicine.

Look at your urine to gauge how well you’re hydrating; it should be pale yellow. Darker urine may be a sign of dehydration. Clear urine, combined with excessive water intake, may suggest overhydration.