The human body is, on average, 60 percent water. So it makes sense that water is doing something important in there. And indeed, water is necessary for almost all physiological processes.In the past few years, research on hydration has shifted from studying the role of hydration in athletic performance to waters role in overall health. And scientists are finding some interesting connections.Water Is Essential to the BodyThere is evidence that insufficient hydration can cause inflammation, stiffen arteries, and interfere with blood pressure control (causing blood pressure to swing wildly from too high to too low). According to a study published in 2022 in the European Heart Journal, staying well-hydrated during middle age can reduce the risk of heart problems later in life.The brain needs water, too. While the research on the cognitive effects of mild dehydration is still sparse and somewhat inconsistent, an increasing amount of evidence shows that the bodys hydration level influences cognitive performance, working memory, and mood.Adam Seal, a scientist who studies hydration physiology and diabetes biomarkers at California Polytechnic, is one of the researchers working to understand how water or a lack of it affects our health.If you dont drink enough water, your blood volume decreases, and the concentration of your blood, specifically your plasma, increases. Your brain responds by secreting the hormone vasopressin. Vasopressin, sometimes called antidiuretic hormone (ADH), helps regulate the amount of water in your body. Vasopressin, he explains, has a lot of downstream effects.Seal and colleagues are discovering that, among other things, vasopressin may act on the liver and the pancreas, setting off a cascade of events leading to problems with glucose regulation.Were certainly not saying that drinking water is going to cure diabetes, he says. But its a low-cost and easy lifestyle change that could potentially have an effect.When you add that to keeping your heart strong, your emotions steady, and your memory sharp, who doesnt want to make sure they get enough water? But how much is enough?How Much Water Do You Need?You may have heard that you need to drink eight glasses of water a day. But that advice is kind of meaningless. Whats the definition of a glass? Fortunately, the National Academy of Medicine (NAM) offers more specific recommendations.According to NAM, on average, men need about three liters of water a day, and women need about two. Thats for plain water, explains Seal. But some of your water comes from food. Melons, lettuce, tomatoes, cucumbers, celery, and spinach are all high-water foods that also offer other important nutrients.Does coffee count toward your fluid intake? After all, its mostly water. The surprising, happy answer is yes! Caffeine is a diuretic, explains Seal. But, his research has shown that it takes much more caffeine than you get in a typical cup of coffee to disturb your fluid balance.Alcohol is another known diuretic. But again, though alcohol does have a dehydrating effect, The good news is that a beer, say, still has a high water content, says Seal, so that offsets some of the dehydration effect. Alcohol is not likely to dehydrate you as long as you dont overdrink.How Do You Know If Youre Getting Enough Water?A good indicator that youre getting enough water is the color of your urine. When youre dehydrated, your urine will be darker. If its clear or pale yellow, then youre probably doing just fine. Another good indicator is how often you urinate. More water, more trips to the loo. And thats a good thing!Generally, thirst is a reliable indicator of when you need to drink, says Seal. However, when youre exercising, that doesnt work so well. Seals research has found that were pretty lousy at estimating how much we need to drink during exercise. So when youre at the gym, on the field, or on the courts, make sure to take regular water breaks, even if you dont feel like you need to. The same goes for any time youre out in the heat.So, do your body a favor. Go, drink some water, and why not have a juicy salad to go with it?Read More: Can Drinking Water Really Help You Lose Weight?Article SourcesOur writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:National Academy of Medicine. Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and SulfateAdam Seal, Assistant Professor at California PolytechnicEuropean Heart Journal. Middle age serum sodium levels in the upper part of normal range and risk of heart failureNutrients. Hydration Status and Cardiovascular FunctionMedical News Today. What is the average percentage of water in the human body?Avery Hurt is a freelance science journalist. In addition to writing for Discover, she writes regularly for a variety of outlets, both print and online, including National Geographic, Science News Explores, Medscape, and WebMD. Shes the author of Bullet With Your Name on It: What You Will Probably Die From and What You Can Do About It, Clerisy Press 2007, as well as several books for young readers. Avery got her start in journalism while attending university, writing for the school newspaper and editing the student non-fiction magazine. Though she writes about all areas of science, she is particularly interested in neuroscience, the science of consciousness, and AIinterests she developed while earning a degree in philosophy.