General recommendation: 0.5 to 1 ounce per pound of body weight daily. 150 lb person: 75-150 oz (2.2-4.4 liters).

More accurate formula: Base need = body weight (lbs) × 0.67 = ounces per day.

Activity adjustment: Add 12 oz for every 30 minutes of exercise.

Climate adjustment: Add 16-32 oz in hot weather (>85°F) or high altitude.

Special conditions: Pregnancy add 24-32 oz, breastfeeding add 32-40 oz, illness (fever/vomiting) add 50-100% more.

Example: 180 lb active person (60 min exercise) in summer: 120 oz base + 24 oz exercise + 24 oz heat = 168 oz (5 liters) daily.

Signs of adequate hydration: Clear to pale yellow urine, urinating every 2-4 hours, no persistent thirst.

Yes, overhydration (hyponatremia) occurs when drinking exceeds kidney filtration capacity (~800-1000 ml/hour or 27-34 oz/hour).

Dangerous when: Drinking >1 liter/hour for several hours, consuming excessive water during endurance events without electrolyte replacement, medical conditions affecting kidney/heart function.

Symptoms: Nausea, headache, confusion, swelling in hands/feet, severe cases can cause seizures or death.

At-risk groups: Marathon runners drinking only water (need electrolytes), people with kidney disease (reduced filtration capacity), psychiatric conditions causing compulsive water drinking.

Safe limits: Healthy adults can safely drink up to 1 liter/hour short-term, 4-6 liters/day long-term.

Prevention: Drink when thirsty, replace electrolytes during heavy exercise (sports drinks with sodium), monitor urine color (aim for pale yellow, not clear).

Rule of thumb: If drinking more than 1 gallon (3.8L) daily without intense exercise/heat exposure, reassess intake.