How Much Water Do You Actually Need?
The popular '8 glasses a day' rule is a myth — water needs vary significantly based on body weight, activity level, climate, and individual health. The most accurate method is based on 35ml per kg of body weight, then adjusted for activity. A 70 kg person needs approximately 2.45 litres at rest, rising to 3.4–3.8 litres with intense exercise.
Water Intake FormulaBase = Weight (kg) × 35 ml
Active: Base × 1.15–1.55
Example: 70kg, moderately active → 70 × 35 × 1.15 = 2,818 ml/day
Active: Base × 1.15–1.55
Example: 70kg, moderately active → 70 × 35 × 1.15 = 2,818 ml/day
Signs of Dehydration
- Mild (1–2% body weight loss): Thirst, darker urine, slight fatigue, reduced concentration
- Moderate (3–5%): Headache, dizziness, dry mouth, reduced physical performance
- Severe (6%+): Rapid heartbeat, sunken eyes, confusion — requires immediate medical attention
💡 Urine colour check: Pale yellow = well hydrated. Dark yellow/amber = drink more water. Clear = possibly over-hydrated (rare but possible).
Hydration Tips
- Drink a glass of water immediately upon waking — your body loses water overnight through breathing
- Carry a reusable water bottle and sip throughout the day rather than drinking large amounts at once
- Eat water-rich foods: cucumber (96% water), watermelon (92%), strawberries (91%)
- Increase intake in hot weather, during illness, pregnancy and breastfeeding
- Sports drinks are only necessary for exercise lasting 60+ minutes; for shorter sessions, water is sufficient
💧 Find your personalised daily water intake — instant result
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