You might need to modify your total fluid intake based on several factors
If you do any activity that makes you sweat, you need to drink extra water to cover the fluid loss. It's important to drink water before, during and after a workout. If exercise is intense and lasts more than an hour, a sports drink can replace minerals in your blood (electrolytes) lost through sweat.
Hot or humid weather can make you sweat and requires additional fluid intake. Dehydration also can occur at high altitudes.
Your body loses fluids when you have a fever, vomiting or diarrhea. Drink more water or follow a doctor's recommendation to drink oral rehydration solutions. Other conditions that might require increased fluid intake include bladder infections and urinary tract stones.
Pregnancy or breast-feeding
Women who are pregnant or breast-feeding need additional fluids to stay hydrated. The Office on Women's Health recommends that pregnant women drink about 10 cups (2.4 liters) of fluids daily and women who breast-feed consume about 13 cups (3.1 liters) of fluids a day.