How much water to drink per day

Water makes up 60% of your body weight and is involved in every biological function. Yet, most people don't drink enough — and the recommendations we hear ("2 liters a day") are too simplistic. Your actual need depends on your weight, activity, diet, and environment.

Steps

1

Estimate your baseline needs

The simple rule: 30 to 35 ml per kg of body weight. For a 70 kg person, that's 2.1 to 2.45 liters per day, including food. Water in fruits, vegetables, and soups counts — it's not just the water you drink.

2

Add 500 ml per hour of exercise

During exercise, you lose 0.5 to 1.5 liters of sweat per hour depending on intensity and heat. Add at least 500 ml per hour of moderate exercise. For intense training or hot weather, go up to 750 ml-1 liter.

3

Account for climate and altitude

Heat, dryness, and altitude increase fluid loss. In summer or at altitude, increase your intake by 500 ml to 1 liter per day. Air conditioning and heating also dry you out — indoor environments aren't neutral.

4

Track your consumption for a few days

Use a marked bottle or count your glasses for 3-4 days. Most people find they drink 30-50% less than necessary. Once you see the numbers, adjusting becomes concrete and motivating.

5

Listen to your body's signals

The color of your urine is the best indicator: pale yellow = well hydrated, dark yellow = drink more. Thirst appears when you're already 1-2% dehydrated. Don't wait until you're thirsty to drink — establish a regular habit.

Why hydration is fundamental

Water transports nutrients, flushes out waste, regulates body temperature, lubricates joints, and supports digestion. Dehydration of just 2% decreases physical performance by 10-20% and measurably impacts cognitive performance. Water is also involved in lipolysis (fat burning) — being chronically dehydrated can hinder weight loss.

Factors that change your needs

Your fluid needs vary greatly depending on the season, altitude, diet type (high salt = more water needed), caffeine/alcohol consumption (moderate diuretic effect), and medications. Pregnant or breastfeeding women have increased needs of 300-700 ml/day. Older adults lose their sense of thirst — they should drink "out of habit" rather than waiting for the sensation.

Recognizing dehydration

The first signs are fatigue, headaches, decreased concentration, and dark urine. Moderate dehydration causes cramps, dry skin, and a high heart rate. In case of dizziness, confusion, or an absence of urine for more than 8 hours, it's a medical emergency. Most people live in a state of slight chronic dehydration without even realizing it.

FoodCraft Tip

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Frequently Asked Questions

Is '8 glasses a day' actually true?
It's a rough approximation. 8 glasses of 250 ml = 2 liters, which fits a moderately active 60 kg person. But someone weighing 90 kg or a very active athlete will need much more. Calculating by kg of body weight is more accurate.
Does coffee dehydrate you?
Not as much as you'd think. Caffeine has a slight diuretic effect, but the water in the coffee more than makes up for it. Up to 3-4 cups a day, coffee contributes positively to your hydration. Beyond that, the diuretic effect becomes more pronounced.
Can you drink too much water?
Yes, it's called hyponatremia—a dangerous dilution of blood sodium. It's rare and mostly affects marathon runners who drink excessively during intense effort. For a healthy adult in daily life, the risk is almost zero below 6-7 liters per day.
Is sparkling water as hydrating as still water?
Yes, exactly the same. Dissolved CO2 doesn't affect water absorption. The only difference: sparkling water can cause bloating in some people. In terms of hydration, it's strictly equivalent.

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