How Much Water Do You Really Need?

You’ve probably heard (or repeated it) this health mantra dozens of times: Everyone should drink eight, 8-ounce glasses of water per day.

But before you fill your cup (again), let’s dive into what the research really says. Eight x 8 is a good place to start, but how much water you need is slightly more nuanced than you might think—especially on a hot July day.

Guidelines

After a study of Americans’ average daily water intake in 2005, the Institute of Medicine (IOM) published the following adequate intake recommendations:

• 3.7 liters per day for men, including about 3 liters (approximately 13 cups) in the form of beverages
• 2.7 liters per day for women, including about 2.2 liters (approximately 9 cups) in the form of beverages.

Notice that this recommendation is for “beverages.” Coffee, tea, soft drinks, sports drinks, juices, and even foods—especially those with high water content, such as fruits and vegetables—all add up toward your total and can help you meet your basic fluid needs.

Choosing the right beverages is important

• Water or other low-calorie beverages, such as plain coffee or tea, or sparkling water are the best choices
• Milk or plant-based alternatives, or 100% vegetable juice, are also good options
• Soda, sports drinks, or other sugary beverages can add many calories to your diet, and they have little nutritional value

Staying properly hydrated contributes to our overall health. One recent study found that poor hydration may accelerate biological aging and increase the risk of chronic disease and death, suggesting that staying properly hydrated might help slow down the aging process.

Five Factors

Scientific American notes that any serious recommendation on how much water (or beverages) we need on a daily basis should take into account more than just an average. Five other factors to consider:

1 Geography and weather

Common sense should kick in here: If the outside temperatures are warm, or if you are in an especially dry, desert-like climate, you’ll need to consumer more water. People are often unprepared for changing weather—the morning starts cool, for example, but by noon the sun is blazing hot. Plan ahead by packing (and drinking) extra water if you’ll be outside.

2 Age

As we age, our sensitivity to thirst can decline and people 70 and older often fail to get adequate hydration. If you or a loved one need help remembering to drink liquids, set a reminder on your phone and keep a cold container handy.

3 Physical condition

People with certain conditions, including kidney stones and diarrhea, need extra water, as do pregnant and nursing women. Research also suggests that if you are trying to lose weight or consume fewer calories, a 16-ounce glass of water before a meal can make you feel more full and less likely to consume extra calories.

4 Activity level

Your body loses water when you sweat, so if you’re outside or getting an especially sweaty workout in, drink a little more water. And if your workout is intense or outdoors, you might consider a sports drink to replace electrolytes. But read labels and watch your sugar intake.

5 Diet

Salty foods can make you feel thirsty. As a result, you’ll probably want to drink more. But too much salt is not good for your overall health, so consider limiting those high-sodium snacks.

Feeling thirsty yet?

Feelings of thirst is the way that our bodies tell us that we need to drink. Pay attention to signs of thirst or dehydration, including:

• dry mouth
• headache
• confusion—a serious sign that you need to get hydrated and may even need to seek medical attention.

Another quick check: When you go to the bathroom, look at your urine. Experts at the Cleveland Clinic say that when you’re healthy and hydrated, your urine should fall somewhere between colorless and the color of light straw and honey. When you don’t consume enough fluids, your more concentrated urine turns a darker yellow or amber color, and you may produce smaller amounts.

How much is too much water?

Can you drink too much water?

Yes. Consuming an excessive amount of water—or in some cases, other underlying medical issues—can lead to a rare but potentially dangerous condition called hyponatremia.

Experts at the Mayo Clinic suggest that, depending on the cause of hyponatremia, you may simply need to cut back on how much you drink, or seek medical help if you notice symptoms like confusion, nausea, or seizures.

Drinking water—especially in these summer months—can help you stay healthy and hydrated. If repeating the eight x 8 rule helps you remember to drink up, you’ll likely be just fine.