How much water should you drink per day?

More than half of your body is water, and virtually every function relies on it. The main reasons to maintain your fluid balance:

• Digestion. Water transports nutrients and removes waste products — not drinking enough can lead to slow digestion and constipation.
• Temperature regulation. When you sweat, exercise, or in warm weather, you lose fluids that you need to replenish quickly to prevent overheating.
• Concentration and memory. Even with mild dehydration, headaches, fatigue, and concentration problems can occur.
• Healthy skin. Sufficient water keeps the skin hydrated and elastic.
• Better sleep. A good fluid balance supports muscles, joints, and hormone balance, helping your body relax better.
• Weight management. Water contains no calories and makes you feel full, so you are less likely to overeat.

The recommended daily amount of water varies for everyone and depends on weight, activity, climate, and age. As a general guideline, approximately 2 liters per day — about 8 glasses of 250 ml — is recommended.

If you want a more personalized recommendation, here's the well-known rule of thumb: body weight in kilograms × 0.033 = liters of water per day. If you weigh 75 kg, you'd need about 2.5 liters. If you exercise intensely or if it's hot, you'll need a bit more — which is exactly what the calculator at the top of this page takes into account.

Do you exercise intensely? Keep in mind that you can lose as much as 2 liters of fluid during an hour of vigorous activity. The rule of thumb: drink back about 1.5 liters per lost kilogram of body weight, spread out over the hours after your workout.

The simplest check: the color of your urine. Light yellow means your fluid balance is good; dark urine is a sign that you need to drink more. Other common signs of dehydration:

• Thirst and a dry mouth (note: the feeling of thirst diminishes as you get older)
• Hunger — your body sometimes confuses hunger and thirst
• Headache, dizziness, or lightheadedness
• Fatigue and poor concentration

In cases of severe dehydration, drowsiness, cramps, low blood pressure, and heart palpitations may also occur. It never has to come to that: anyone who drinks small amounts regularly will stay well hydrated.

Yes, although it's rare. Your kidneys process about 0.7 to 1 liter per hour; if you consistently drink much more than that, your blood sodium levels can drop too low. This is called water intoxication and is primarily a concern in extreme endurance sports, such as marathons lasting more than four hours.

For almost everyone, the rule is: spread your water intake throughout the day, drink when thirsty, and you'll be fine. Your sense of thirst is and remains the best natural indicator.

Drinking enough is mainly a matter of making it easy for yourself:

• Keep your bottle in sight. A water bottle on your desk or in your bag is the simplest reminder there is — what you see, you grab.
• Link it to fixed moments. A glass when you wake up, a sip with every coffee, refilling your bottle after lunch. Habits work better than good intentions.
• Give your water flavor. If you find water boring, add fruit, cucumber, or mint.
• Choose a reusable stainless steel bottle. Tap water in the Netherlands is excellent, so a good bottle is all you need. Stainless steel is also easy to keep clean, preventing bacteria from getting a chance — rinsing daily with warm water and dish soap is sufficient.