Maybe you’ve seen those people lugging around gargantuan water jugs. And maybe you’ve chortled at them, just a little bit. But perhaps it’s gotten you thinking. How much water do we really (truly) need each day? And why?

Water is your body's primary chemical component and makes up about 50% to 70% of your body weight. Every cell, tissue and organ in your body needs water to work properly. Water is essential for:

• Carrying nutrients and oxygen to your cells
• Aiding digestion
• Normalizing blood pressure
• Stabilizing heartbeat
• Lubricating and cushioning joints
• Protecting organs and tissues
• Regulating body temperature
• Maintaining electrolyte (sodium) balance
• Flushing bacteria from your bladder
• Preventing constipation
• Getting rid of body waste

Lack of water can lead to dehydration, a condition that occurs when you don't have enough water in your body to carry out normal functions. Even mild dehydration can drain your energy, make it difficult to concentrate, and even leave you feeling nauseated. For your body to function properly, you must replenish its water supply by consuming beverages and foods that contain water. But how much? Studies have arrived at varying recommendations over the years. And your individual water needs depend on many factors, including your health, how active you are and where you live.

The U.S. National Academies of Sciences, Engineering, and Medicine determined that an adequate daily fluid intake is:

• About 11.5 cups (2.7 liters) of fluids a day for women
• About 15.5 cups (3.7 liters) of fluids a day for men

Since water is vital to our daily functioning, is there is a benefit to drinking, say, a gallon or more of water? Not according to experts. Because contrary to what many people believe, exceeding our fluid needs provides no additional benefit. In fact, people who drink too much water, in the absence of electrolytes, run the risk of developing hyponatremia, a life-threatening condition characterized by low sodium levels in the blood that occurs with overhydration.

So how do you know if you’re drinking enough? Your fluid intake is probably sufficient if you rarely feel thirsty and your urine is colorless or light yellow. Your doctor or dietitian can help you determine the daily amount of water that's right for you.