How Much Water Do You Need

By Barbara Gordon, RDN, LD
Woman with water

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When it comes to how much water to drink daily, most people recite the 8 x 8 rule. But, do you really need to drink eight 8-ounce glasses, or 64 ounces, of water every day?

Water is Essential to Life

About 60 percent of your body is made of water. It plays a role in keeping all of your body systems working well. Staying well hydrated can help reduce your risk of developing kidney stones, urinary tract infections and constipation.

You lose water throughout the day with normal body processes, such as making urine, having bowel movements and sweating. Very active individuals can lose more water through sweat, as the body tries to cool itself down. The same is true at higher altitudes and when you are out in extreme temperatures. Plus, illnesses such as fever and diarrhea promote additional water loss.

The Risks of Dehydration and Overhydration

 If you lose more water than you take in, your body can become dehydrated. Dehydration can wreak havoc on your body, causing headaches, dizziness or digestion problems. Mild dehydration may impact your mood, memory or how well you're able to process information. These symptoms often go away once your body gets rehydrated. Medical attention is often needed with severe dehydration, since it can lead to more serious problems such as confusion, kidney failure, heart problems and possibly death.

It is also possible to become overhydrated. Although this is not as common, athletes and individuals with certain medical conditions may be at higher risk for overhydration. Symptoms of severe overhydration are often similar to dehydration and may also require medical attention. For example, confusion and seizures can occur. Individuals participating in long stretches of physical activity, such as marathons, often need to replace both water and sodium losses. In these events, a hydration schedule is usually followed, and beverages such as sports drinks may be recommended.

Fluid Needs Vary

Many factors impact how much water you need, including your age, gender, activity level, and overall health. Women require more water during pregnancy and while they are breastfeeding. Individuals with certain health conditions, such as congestive heart failure or renal disease, also have different fluid needs. The same is true for those with serious infections or diarrhea.

Adequate intake levels for water have been determined for generally, healthy people and are based on age and gender.

For women, the amount of total water is about 11.5 cups per day and for men about 15.5 cups. These estimates, however, include fluids consumed from both foods and beverages, including water. You typically get about 20% of the water you need from the food you eat. Taking that into account, women need about nine cups of fluid per day and men about 12.5 cups in order to help replenish the amount of water that is lost.

Color Check

A quick and easy way to check if you are getting enough water overall is to take a peek at the color of your urine. If you are consuming enough, the urine color will be a pale yellow color. If it is a dark yellow or amber color, you may need to increase the amount you consume.

Sources of Water

It's important to replace those water losses to stay in good health. You can do this by enjoying a variety of beverages, as well as eating foods that have a high water content, such as fruits and vegetables. For drinks, focus on unsweetened beverages, like water, in order to limit calories from added sugars.

Ways to Increase Water

  • Listen to your body: If you are thirsty, drink water. This is especially important if you are active or live in very hot climates.
  • Opt for water: Instead of soda or energy drinks go with a tall glass of water.
  • Drink water throughout the day: Consume water with meals, as well as between meals.
  • Carry a refillable water bottle: Keep water handy, so it's there when you want to reach for a drink.
  • Add a flavor enhancer: For variety, squeeze some fresh lemon or lime juice into your water, toss in a couple of cucumber slices or add a few fresh basil leaves.

Foods That Are High in Water

Options with a 90-100% water content, include:

  • Drinks like water, sparkling water and fat-free milk.
  • Fruits, especially cantaloupe, strawberries and watermelon.
  • Vegetables like lettuce, cabbage, celery, spinach and cooked squash.

Options with a 70-89% water content, include:

  • Fruits including bananas, grapes, oranges, pears and pineapples.
  • Vegetables such as carrots, cooked broccoli and avocados.
  • Dairy products like yogurt, cottage cheese and ricotta cheese.

Need Help Figuring Out Your Fluid Needs?

A registered dietitian nutritionist (RDN) can help you estimate your fluid needs. Ask your health care provider for a referral to an RDN. Or, use the Academy’s Find an Expert tool to locate an RDN in your area.

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