Summer Hydration: The Truth Your Doctor Isn't Telling You
2 liters of water a day in summer is the standard recommendation. But during a heatwave, physical activity, or a day at the beach, this amount can be largely insufficient. Here's what you really need to know.
How much should you really drink in summer?
The simplified formula: your weight (kg) × 30 = ml of water per day under normal conditions. But in summer, add: +500ml per hour of intense physical activity, +500ml per 10°C above 20°C, +500ml if you spend more than 2 hours in direct sunlight. For a 70kg person at 35°C with one hour of sport: 2100ml + 750ml (heat) + 500ml (sport) = 3.35 liters minimum.
Early signs of dehydration
You're already dehydrated when you feel thirsty—that's the first late sign. Instead, watch for: dark urine (dark yellow = drink immediately), slight headaches in the middle of the day, mild confusion or difficulty concentrating, unexplained fatigue despite a good night's sleep.
Still water vs sparkling water vs sports drinks: what to choose?
Still water: the basic. Hydrates effectively but does not compensate for mineral salts lost through perspiration. Sparkling water: as hydrating as still water, despite common misconceptions. But it satiates quickly, which can lead you to drink less. Isotonic sports drinks: only relevant for intense efforts lasting more than 1 hour. Too sugary for daily hydration. Water with electrolytes (magnesium, sodium): the best solution in case of extreme heat or after intense activity. A pinch of salt + lemon in your bottle will do the trick.
Hydrating foods
25% of our water needs come from food. Summer champions: cucumber (96% water), watermelon (92%), tomato (94%), strawberry (91%), zucchini (94%), melon (90%). A mixed salad in summer can provide you with 300-400ml of water.
Hydration mistakes to avoid
❌ Drinking 1 liter all at once — the body can only absorb 200-300ml at a time. ❌ Compensating with coffee or tea — diuretics, they increase water loss. ❌ Waiting until you're thirsty to drink — schedule small amounts every 30 minutes. ❌ Forgetting to drink when in cool water (pool, sea) — you also sweat in water.
Mister: hydration through the skin?
No — a mister does not replace drinking. But it lowers skin temperature, reduces perspiration, and thus slows down water loss. A rechargeable USB facial mister at your workplace or outdoors perfectly complements a good hydration strategy. Code ETE2026 for -15%.
Stay cool and well-hydrated this summer 2026! 💧☀️