Water: how much, when, and why it matters

Your personal target is computed from your weight — here is the background.

• •A common rule of thumb: about 30–35 ml per kg of body weight per day, and more in heat, during exercise and while breastfeeding.
• •Even mild dehydration of 1–2% hurts concentration and mood, and sometimes masquerades as hunger.
• •Urine color is the simple gauge: pale yellow = you are doing fine.
• •Spreading it through the day beats a liter in one go — which is why the reminders are spaced between 10:00 and 20:00.

General information — not a substitute for personal medical or nutritional advice.