Your body is about 50–60% water. Thirst, kidneys and hormones keep water and electrolytes within a narrow range.
How it works, step by step
Water lost through breath, sweat and urine raises blood concentration.
The brain senses it and triggers thirst plus antidiuretic hormone.
Kidneys conserve water; urine gets darker.
Drinking restores balance.
How much
Needs vary with climate, activity and body size. About 20% of total water typically comes from food.
Can you get too much Hydration & Electrolytes?
Drinking very large amounts quickly, especially during long endurance events, can dilute blood sodium (hyponatremia).
Evidence & sources
Most healthy people meet their daily water needs by letting thirst guide them. Evidence: established. Known: Conclusion of the National Academies' water review. Unknown: Does not apply during intense exercise, extreme heat, or certain medical conditions. Source: National Academies (Institute of Medicine), Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate (2005).