The Ultimate Guide For Staying Properly Hydrated (Yes, Drinking Too Much Water Is A Thing)

Updated July 10, 2025 at 6:00pm*

HAMBURG — Summer is here, hot days are upon us, and one thing we’ve been taught is that drinking enough water is essential. But what does “enough” actually mean? Does that fifth coffee count? And when does the compulsion to always hydrate go overboard?

Anyone who starts the day with a big cup of coffee has already done something good for themselves, and may not need to carry around an oversized Stanley Cup to stay hydrated. Yes, that’s the first piece of good news when it comes to drinking enough liquids: coffee counts.

But now for the less encouraging part: figuring out how much you should drink each day is complicated. The common rule of thumb that you need to drink two liters of water every day isn’t accurate — or at least only applies to a small number of people.

How much fluid you actually need to take in through drinks varies greatly and depends on many factors. The most important are age, body weight, gender, diet, and physical activity.

On average, men use about 4.3 liters of water per day, while women use about 3.4 liters. In men, this water turnover begins to decline around age 40, while in women, it decreases only after age 65. This is partly due to a slower metabolism and decreasing muscle mass. The differences from the average can be significant: some people use only one to one and a half liters per day, while others use up to six liters.

But that doesn’t mean anyone needs to drink six liters a day: more than half of the water our body uses daily doesn’t come from drinks, but from solid food, is produced during digestion, or is absorbed through the skin.

There is, however, a guideline for beverages. But it’s not two liters — it’s an average of 1.5 liters per day. This is recommended by several health insurance providers as well as by the German Nutrition Society (DGE). This amount applies to healthy individuals who eat a balanced diet — for example, one that includes plenty of vegetables. The DGE also recommends “ideally drinking water or other calorie-free beverages such as unsweetened tea.”

From this recommendation, individuals can assess whether they need more water depending on their body and level of activity. Men, younger adults, people with higher body weight, or those who are very active should drink more. Pregnant women, breastfeeding women, and people between the ages of 15 and 25 have the highest water requirements.

How do I know if I’m drinking enough?

The most important indicator of proper fluid intake is, of course, thirst. If you feel thirsty, you shouldn’t wait to drink. But thirst tends to decrease with age, and even before that, it’s not always reliable.

Humans are creatures of habit

There are other signs that may point to dehydration, or at least to a slightly low fluid intake: feeling tired despite getting enough sleep, dry skin or dry eyes, being more sensitive to cold, headaches, lack of energy, or circulation problems. Less urine or dark yellow urine can also be a sign that you should be drinking more.

However, all of these symptoms can also have other causes. The most reliable method for ensuring you drink enough is to keep track of how many glasses you drink per day.

How do I remember to drink enough?

Humans are creatures of habit. People who tend to drink too little need to develop new routines in order to adjust in the long term. This is no small task, especially when it comes to nutrition – and on average, it takes about 59 days, and even longer for about half of all people. The most important thing is to keep going. And rather than setting an abstract goal like “drink more,” it helps to make small, specific changes.

This could mean always taking a water bottle with you — whether on the way to work, on the train for a vacation, during exercise, or just while walking around the neighborhood.

If you are spending a lot of time in one place, such as at your desk, it helps to always have a glass of water in sight and within reach. People at work need to be especially careful; they are more likely than others to drink too little due to the demands of their job. Another good habit is to drink a glass of water before every meal.

What’s the right balance between water and electrolytes?

In most cases, drinking more water is a good idea. People are much more likely to drink too little than too much. But there is a limit. The body needs to maintain a balance between water and electrolytes. If you drink too much water too quickly, this balance can become just as disturbed as it would if you drank too little.

About one-third of marathon runners drink too much water during a race.

If the concentration of electrolytes such as sodium or potassium in the blood falls too sharply, it can affect things like the nervous system and muscle function. Drinking too much water in a short period of time can even be life-threatening.

People who are more physically active also need to drink more. But even with intense exercise, there is a limit — and many amateur athletes go over it. According to data from the Barmer health insurance provider, about one-third of marathon runners drink too much water during a race. In up to five out of every 1,000 cases, this can lead to life-threatening changes in the composition of the blood.

In 2015, a 30-year-old amateur athlete died after the Ironman in Frankfurt am Main because he had consumed too much water — without taking in electrolytes, for example through salt or fortified beverages.

Most people, however, do not need to take additional electrolytes; they usually get enough through their diet. Only people who lose a great deal of water should consider sports drinks or salty snacks. This applies, for example, to people who do physical labor or exercise for long periods in extreme heat. But it can also be useful after vomiting or diarrhea.

Does it always have to be pure water?

No. A surprising result of a randomized U.S. study from 2016 showed that after drinking a glass of juice or lemonade, a cup of tea or coffee, or even a light beer, the body does not excrete significantly more urine than after drinking the same amount of pure water.

So, staying hydrated does not require drinking only water — coffee counts as well. However, this says nothing about the other health effects of those drinks: the sugar in juices and lemonades (especially in large amounts), and the alcohol in beer, are still harmful. So, water remains the best option, but it does not have to be the only one

What about children?

Babies who are still exclusively breastfed do not need additional water. But parents should still make sure that their children drink enough once they are no longer breastfeeding. Although children’s thirst is usually more reliable than that of adults, they can still forget to drink if they are focused on playing.

In general, it is enough to regularly offer unsweetened beverages. According to DGE, less than one liter of water per day is enough for children under 10. After that, the need for fluids steadily increases; from the age of 15 onward, the recommended amount is one and a half liters per day.

Can I just drink one and a half liters in one go?

Anyone worried about forgetting to drink enough during the day might think they can get ahead of the problem: just drink three half-liter glasses of water first thing in the morning – and you’re done.

But it doesn’t work that way. You cannot store water. The digestive system can only absorb a certain amount of fluid per hour — the rest is excreted without being used. Figures vary slightly on how much that is exactly: some sources say about 200 milliliters every 15 minutes, others suggest between 500 and 800 milliliters per hour.

Either way, drinking a lot of water all at once is not helpful for staying hydrated, and can be harmful. Instead, you should spread out your fluid intake throughout the day — for example, two to three glasses in the morning, at lunchtime, and in the evening, or simply one glass every one to two hours.

Should I drink something with meals?

There is very little research on whether drinking fluids with meals helps digestion. Some have even suspected that it might be harmful because it could dilute stomach acid. But that has been disproven. The dilution effect is minimal, and stomach acid remains stable even after drinking a large glass of water. Another theory that has not yet been clearly proven is whether drinking before a meal helps with weight loss.

It is true that a full stomach sends signals to the brain that reduce appetite. And drinking a glass of water before eating will naturally help fill your stomach. However, studies are still inconclusive as to whether this significantly reduces calorie intake and supports long-term weight control.

Cold or warm water when it’s hot?

On hot summer days, people usually fall into one of two camps: some reach for ice cubes with a little water in between, while others drink only hot tea all day long. The two sides have different theories. Some believe cold water cools the body from the inside, while hot drinks only increase body temperature. Others say cold water signals the body to raise its internal temperature, while hot tea or coffee sends a signal to cool down.

Scientific studies now clearly support the second group. A hot drink increases sweating, and the extra sweat cools the body more effectively than cold water — and across all areas of the body. But this only works if the sweat can evaporate to cool the skin. If a lot of clothing covers the skin, sweat has less of a cooling effect.

The Consumer Protection Agency still advises avoiding both extremes. The best choice is to drink water that is at room temperature or slightly warm. Ultimately, you simply need to drink more in extreme heat. So choose a drink you enjoy. If hot tea feels too warm, unsweetened iced tea is a good alternative.

*Originally published July 2, 2025, this article was updated July 10, 2025 with enriched media.