Most of us know we should be drinking water. After all, it accounts for 50–60% of an adult’s body composition. We lose water even when we’re at rest, through functions such as breathing and perspiration. Certain factors—from age to activity level—amp up our need for water even further. (More on those factors in a minute.)
When we don’t get enough water, we generally don’t feel good. Being under-hydrated by as little as 2% can bring on headaches, fatigue, and other forms of discomfort.
The question is: How much water do we really need to drink? Many of us were taught the “8 x 8” rule as children, which calls for eight 8-ounce glasses a day. Or, maybe you’ve heard that it’s best to “chain sip” water throughout the day, regardless of thirst or other variables. In reality, our water needs are far more nuanced: There’s no one-size-fits-all recommendation for how much water to drink, and the number of glasses you need is specific to you.
How to calculate your ideal daily water intake
Multiple factors affect a person’s fluid requirements. These include:
To gain a baseline understanding of your personal water needs, pull out a calculator and do this quick math:
• If you're younger than 30, multiply your weight (in lbs) by 0.642
• If you're 30-55 years old, multiply your weight (in lbs) by 0.56
• If you're older than 55, multiply your weight (in lbs) by 0.481
For example, for a 50-year-old person who weighs 180 pounds:
It’s important to remember that this calculation will not produce an exact measure of your water needs, and that it reflects your approximate baseline water requirement from all sources, including food.
How to know if you’re drinking enough water
No formula needed for this one: To check if you’re hydrated, take a quick look at your urine. If it’s pale yellow, you’re probably drinking enough water. On the other hand, a dark yellow color could be a sign that you need to amp up your hydration. Just bear in mind that urine color isn’t a perfect indicator. A darker color can also result from certain health conditions, medications, vitamin B2 supplements, and natural pigments in certain foods.
Know the other signs of dehydration
That’s why it’s helpful to be on the lookout for other signs that your water intake might be too low. Dehydration can also be marked by:
Dehydration is associated with kidney stones. Otherwise, there’s little evidence linking dehydration with chronic disease. Occasional bouts of mild dehydration are common.
Thirst isn’t always first
Dehydration can kick in before you feel parched. By the time you notice a dry mouth, your mood or concentration may already be affected by having too little water in the body. Keeping a refillable water bottle handy can be a visual reminder to sip regularly, before headaches and other forms of discomfort hit.
How can you increase your water intake?
If you’re thinking, “There’s no way I can chug so much plain water every day,” you have additional options for staying hydrated:
Can drinking water help you lose weight?
Research has not established a direct link between water intake and weight loss. Water can support weight loss, however, when it takes the place of sugar-sweetened soft drinks. Unlike a can of sugary cola, water delivers hydration without adding calories to a person’s overall diet.
Other health benefits of drinking water
Good hydration is essential for:
In a nutshell, water helps the entire body function at its best.
The upshot: Are you drinking enough water daily?
To boil it down, staying hydrated is important for your overall wellness journey. Because the body loses water throughout the day, replenishment is crucial for preventing dehydration. Your age and weight are key factors in how much fluid you need, with variables such as activity level and diet further influencing day-to-day water needs. Speak with a medical professional if you have any concerns about hydration and your health—especially if you notice unexplained changes in your level of thirst or in your urinary habits.