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How Much Water is Too Much? (Yes, There’s Such a Thing)

by jeannie assimos on July 18, 2025

For something that doesn’t taste like much, water sure gets a lot of attention. Everywhere you turn, someone’s sipping from a massive bottle, tracking hydration on an app, or explaining how they “just feel better” after their third liter. Somewhere along the way, staying hydrated turned into a hobby and not always a healthy one.

Yes, your body needs water. But the truth is, drinking too much water can actually be harmful, and it’s more common than you’d think, especially when the pressure to hydrate comes not from thirst but from trends, challenges, and very persuasive wellness influencers.

 

So, how much water is actually too much? When does it cross the line?

The 8-glass rule: Where it came from, and why it stuck around

“Drink eight glasses of water a day.” It's a catchphrase that's simple, and easy to remember. It’s the kind of advice that shows up in brochures, wellness newsletters, and more than a few water bottles. But for all its popularity, no one’s really sure where it started or why it refuses to go away.

Some trace it back to a 1945 guideline from the U.S. Food and Nutrition Board. The original recommendation? About 2.5 liters of water per day. What often gets left out is the fine print; most of that water comes from food. Think watermelon, cucumbers, soups, and even your morning coffee.

Still, the idea of drinking eight full glasses of plain water took off. It sounded scientific enough, and it was easy to market. Never mind that it ignored things like body size, activity levels, or whether you live in Tucson or Portland.

The truth is that hydration needs vary from person to person. The 8-glass rule is more tradition than truth; helpful for some, irrelevant for others.

 

What your body actually needs

Your hydration needs aren’t fixed. They change based on your size, activity level, environment, and even what you eat. Some days you’ll need more, other days less. It’s not a perfect science.

The Mayo Clinic suggests that healthy men need about 3.7 liters (15.5 cups) of fluids a day, and healthy women need around 2.7 liters (11.5 cups). This includes water, yes, but also drinks like coffee and tea, plus water-rich foods like fruit, vegetables, and soups.

That means your smoothie, your oatmeal, and even that orange you grabbed between Zoom calls all contribute to your daily intake.

Rather than counting glasses, it makes more sense to pay attention to signs. Thirst, dry mouth, dark yellow urine, and low energy are all better indicators than a hydration app or a trending goal. And if you're drinking just to check a box, it might be worth listening to your body instead.


What happens if you drink too much water 

Water is essential, but your body has limits. When you drink more than your kidneys can flush out, especially in a short period of time, you risk a condition called water intoxication.

Water intoxication is what happens when your system gets overwhelmed. The excess water starts to dilute your blood’s sodium levels, which can lead to hyponatremia, a potentially serious condition where your cells begin to swell. That includes brain cells, which is when things can take a dangerous turn.

This isn’t common, but it’s not unheard of. Endurance athletes, people on extreme detoxes, and even participants in water-drinking contests have landed in the ER because of it.

 

Symptoms of water intoxication (and resulting hyponatremia) can include:

  • Headache
  • Nausea or vomiting
  • Bloating
  • Confusion or disorientation
  • Muscle cramps or weakness
  • Fatigue
  • In severe cases, seizures, coma, or death

Most healthy kidneys can process about 0.8 to 1.0 liters of water per hour. Go far beyond that, especially without replacing electrolytes, as your body may struggle to keep up.

This doesn’t mean you need to worry every time you reach for your bottle. But it’s a reminder that your body already knows how to manage hydration, and more isn’t always better.

 

How do you know you're drinking the right amount of water?

Your body will tell you when you need water. You don’t need a tracker or reminders about how much to drink. Just pay attention and drink when you're thirsty. 

These are your body's signals: 

 

  • Thirst is the most important and reliable signal. You don't always need to try and preempt.
  • Urine color is a simple way to check your hydration level. Pale yellow usually means you are well-hydrated. However, if your urine is constantly clear, it might mean you are drinking more water than you need.
  • Energy and focus can dip when you're not getting enough water. Consider fluids if you're feeling unusually tired or foggy, especially after physical activity.
  • Overhydration signs matter, too. Needing to urinate every hour, waking up multiple times at night, or feeling bloated can mean you're drinking way more than your body wants.

You don't really need to meet a quota. You need to stay in balance. Some days that might mean more water, and some days, less. Most of the time, your body knows before any chart does.

How to tell if you’re drinking the right amount of water
Instead of following a fixed number, it helps to understand how your body manages water throughout the day.

According to a large-scale hydration study published in Science, adult water turnover is the total amount of water your body uses and replaces each day. For most people, this falls between 2 and 4.5 liters, depending on age, body size, activity level, climate, and diet.

That range includes all fluids. It covers what you drink, what you eat, and what your body generates during digestion and metabolism. If you’re exercising, spending time in heat, breastfeeding, or eating a high-protein diet, your hydration needs will lean higher.

What matters most is not the number but the range. Rules like “8 glasses a day” ignore how much your fluid needs change across different days and situations. Some people need more, others less, and most fluctuate depending on weather, food, and movement.

If you stay within that range and adjust based on how you live and feel, you’ll likely land in the right spot without needing to count every sip.

 

What matters most

Water is vital, but like most good things, it works best in balance. You don’t need to count every ounce or chase extreme targets. Most days, listening to your body will get you further than any hydration challenge ever could. 

The science is simple. Your kidneys know what to do. Your body speaks up when it needs more. And when it’s had enough, it lets you know that too as long as you’re paying attention.

At mainelove, we’re all for quiet habits that actually support your well-being and hydration is key among them.

Image: Zack Bowen/Maine Studio Works

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