Water accounts for more than half your body weight; every cell needs it to function properly. It’s essential for carrying nutrients, flushing toxins, and powering your immune system. While experts recommend drinking water whenever you feel thirsty in order to replenish lost fluids, several factors affect your individual need:

• Exercise. Before a workout, be sure to drink one to two cups of water. Keep water handy during exercise, then fill up again afterward with two to three cups.

• Environment. Hot or humid weather, high altitudes, and dry environments will increase your hydration needs.

• Illness. When you have a fever, vomiting, or diarrhea, your body will need additional fluids. If you have a bladder or urinary tract infection, extra water may help clear it.

• Pregnancy or breast-feeding. The Institute of Medicine recommends that pregnant women drink about 10 cups a day; and the recommendation is 13 cups for breast-feeding moms.

The best way to determine if you’re getting enough liquid is to check the color of your urine — if it’s dark yellow, you need to drink more. Just remember, it can be dangerous to drink too much water. Pay attention to your thirst and how you feel as drink water throughout the day.