How Much Water Should You Actually Drink Per Day? (The Science-Backed Answer)

Debunking the '8 Glasses' Myth

For decades, health advocates have repeated the rule of thumb that everyone should drink eight 8-ounce glasses of water per day. However, this advice has no actual scientific basis. Your hydration needs are highly dynamic and depend on your body weight, metabolism, sweat rate, current climate, and activity levels.

Consuming too little water causes dehydration, while drinking too much can dilute sodium levels in your blood, a dangerous condition called hyponatremia.

A Science-Backed Hydration Formula

Medical experts recommend using body mass as a baseline, then adjusting for physical activity:

• Baseline: Drink approximately 35ml of water per kilogram of body weight (approx. 0.5 oz per pound).
• Exercise: Add 350ml (12 oz) of water for every 30 minutes of moderate-to-high intensity exercise.
• Climate: Add 500ml - 1000ml in high humidity, extreme heat, or high-altitude environments.