How much water should I drink per day?

The German Nutrition Society recommends 35ml per kilogram of body weight as a guideline. At 75kg, that's about 2.6 liters. With exercise, heat or pregnancy, the requirement increases significantly.

Do coffee and tea count toward water intake?

Yes, coffee and tea contribute to fluid intake. However, caffeine has a mild diuretic effect, which is why we add about 150ml extra per cup. Overall, they do count toward your daily intake.

Can you drink too much water?

Yes, excessive drinking (hyperhydration) can dangerously lower blood sodium levels (hyponatremia). But this only happens at extreme amounts of over 6-8 liters in a short time. Normally, the body regulates excretion reliably.

How do I know if I'm not drinking enough?

Typical signs include dark urine, headaches, fatigue, dry lips, concentration problems and dizziness. A simple test: if your urine is light yellow to clear, you're drinking enough.

Do I really need more water during exercise?

Yes, during exercise you lose 0.5 to 2 liters per hour through sweating. For moderate exercise we recommend 500ml extra, for intense sports up to 1,500ml. Ideally drink small amounts every 15-20 minutes.

Why do I need more water in summer?

In high temperatures, the body sweats more to cool down. In warm weather, needs increase by about 400ml; in extreme heat, by 800ml or more daily.

How much should pregnant and nursing women drink?

Pregnant women need about 300ml more per day for amniotic fluid formation and increased metabolism. Nursing mothers need up to 700ml more, as breast milk is about 87% water.

Does the water in food count?

Yes, about 20% of your water needs are covered by solid food. Fruits and vegetables like cucumber (96% water), watermelon (92%) or tomatoes (95%) are particularly water-rich.

Is mineral water better than tap water?

German tap water is strictly regulated and excellent in most regions. Mineral water provides additional minerals like calcium and magnesium depending on the brand. Health-wise, there's little difference.

How can I build a habit of drinking more water?

Keep a filled water bottle at your desk, drink a glass right after waking up and set hourly reminders. Water with lemon, cucumber or mint also adds variety.

Coffee and Water Intake: Does Caffeine Really Dehydrate Your Body? | Water Intake Calculator

Coffee and Water Intake: Myths and Facts

Does coffee really dehydrate the body? This question is one of the most persistent nutrition myths. Time for an update based on current science.

The Myth: Coffee Dehydrates

For generations, the advice was: every cup of coffee needs a glass of water alongside it because coffee drains fluid from the body. This recommendation stems from a 1928 study that is now considered outdated.

What Science Says

Modern studies show a more nuanced picture:

University of Birmingham Study (2014)

Men who drank 4 cups of coffee daily were just as well hydrated as those who drank the same amount of water. Hydration measurements (urine osmolality, body weight, blood markers) were identical.

PLOS ONE Meta-Analysis (2019)

An analysis of 16 studies confirmed: moderate coffee consumption (3-5 cups/day) has no dehydrating effect. The body adapts to caffeine's diuretic effect.

How Caffeine Actually Works

Caffeine has a mild diuretic effect. It slightly blocks ADH (antidiuretic hormone), which can temporarily increase urine production. But:

- A cup of coffee contains about 200-250 ml of liquid

- The diuretic effect amounts to only about 50-80 ml per cup

- Net, coffee contributes positively to your fluid balance

Why We Still Recommend 150ml Extra

In our calculator, we factor in 150 ml per cup of coffee as an addition. This is a conservative safety buffer covering two scenarios:

1. Occasional coffee drinkers: the diuretic effect is stronger for them than for regular drinkers

2. Strong coffee: espresso or cold brew contain more caffeine with less liquid

Coffee Types Compared

**Filter coffee (250 ml):** ~95 mg caffeine, moderate diuretic effect

**Espresso (30 ml):** ~63 mg caffeine, little liquid -- here the extra glass of water is worthwhile

**Cappuccino (200 ml):** ~63 mg caffeine, plus milk as a fluid source

**Cold brew (250 ml):** ~200 mg caffeine, stronger diuretic effect

Recommendation

Enjoy your coffee without guilt. It counts toward your fluid intake. The extra glass of water alongside is a good habit, but not a medical necessity. With more than 4-5 cups daily, however, you should consciously pay attention to additional water intake.