In the early 19th century, water was not regarded as essential in daily life as it is today.

Back then, people believed that drinking water was only necessary in extreme situations, such as when someone was extremely poor or on the verge of death.

Vincent Priessnitz, the founder of hydrotherapy, pointed out that drinking boiled water to quench thirst was often a desperate measure, and most people would not drink more than half a pint of water at a time. However, as society evolved, so did our understanding of the importance of water.

Today, drinking water has become a fundamental part of a healthy lifestyle. In the UK, the amount of water adults consume daily has steadily increased, and in the United States, bottled water sales have even surpassed those of carbonated drinks.

Various health guidelines advocate for drinking large amounts of water daily, such as the popular "8x8 rule," which suggests drinking eight 240 ml glasses of water a day.

However, this rule is not supported by strong scientific evidence. No official health organization explicitly recommends that adults must drink that much water every day.

This misconception may stem from outdated guidance. In 1945, the U.S. National Research Council recommended that adults consume fluids in proportion to the calories they intake. Based on this recommendation, women need about 2 liters of fluids for a 2,000-calorie daily diet, while men typically require more.

However, this guidance does not specifically state that all fluids must come from water. Other sources, such as water found in fruits, vegetables, coffee, and tea, also contribute to overall hydration.

Water is undoubtedly the source of life, making up about two-thirds of the human body. It plays various crucial roles, such as transporting nutrients, regulating body temperature, and lubricating joints.

We lose water through sweating, urination, and even breathing, so maintaining proper hydration is crucial to preventing dehydration. When we lose 1-2% of the water in our bodies, the symptoms of dehydration begin to appear.

Some people worry that thirst is a sign of severe dehydration, so they force themselves to drink large amounts of water throughout the day. However, scientists have found that the thirst mechanism is quite precise. When we feel thirsty, our body signals that it’s time to replenish water, and there is no need to panic.

As Dr. Dan Kipps, a sports medicine expert at University College London, explains: "The human body has evolved a highly complex system for managing hydration, and it ensures water balance through various mechanisms."

While the benefits of staying hydrated are well-established, drinking more water than the body requires does not necessarily provide additional advantages. Research has shown that moderate hydration can improve cognitive function and help us perform simple tasks more efficiently.

Some studies have also suggested that drinking water may aid in weight control. For instance, one study found that drinking water before meals could assist with weight loss because it promotes a sense of fullness.

However, whether water directly contributes to weight loss remains a subject of debate. In reality, the primary benefit of drinking water for weight management is that it helps reduce the consumption of high-calorie beverages.

Moreover, although there are claims that drinking more water improves skin quality and moisturizes the skin, there is currently insufficient scientific evidence to support this assertion.

Although drinking large amounts of water is generally harmless for most people, excessive water consumption can lead to serious health issues in certain cases.

For example, drinking too much water can dilute the sodium in the bloodstream, leading to a condition known as hyponatremia, which can cause life-threatening complications like brain swelling.

In endurance sports, such as marathons, overhydration has led to dangerous consequences. For instance, Pakenham, a participant in the 2018 London Marathon, was rescued after falling into a coma due to overconsumption of water.

So, how much water should we drink? Experts generally agree that individual water needs vary depending on factors such as age, body size, environment, and physical activity.

On average, adults only need to consume 6-8 glasses of fluids per day, and these fluids are not limited to water—they can also include beverages like tea or coffee. For older adults, maintaining good hydration habits is especially important, as the body's natural thirst signals tend to diminish with age.

In the end, there is no need to obsess over meeting the "8 glasses of water" guideline every day. Just as the body sends signals when we are hungry or tired, it also communicates when we need water, primarily through the sensation of thirst.

Drinking water should be based on moderation and listening to our body's needs, rather than blindly adhering to a rigid rule in the pursuit of health.