Ask LH: How Much Water Do I Actually Need To Drink Every Day?

Dear Lifehacker, I’ve heard you need eight glasses of water every day, but I’ve also heard that it might be more or less. Some say too much water is bad, and many more say too little is bad. How can I know if I’m getting the right amount if nobody really knows what that amount is? Please help! Sincerely, Dumbfounded Drinker

Pictures: stocknadia (Shutterstock), Milia Liu (Shutterstock), Boris Franz (Shutterstock), ElenaGaak (Shutterstock)

Dear D.D.,

While a lot of people may disagree about the exact amount of water you should drink each day, and that your needs will differ from others with different body types. While no specific measurement will fit all people, I consulted Dr Pamila Brar to get some basic guidelines. She suggested the following, presuming a temperate climate:

  • Men should drink about 3 litres (about 13 cups) of total fluids a day
  • Women should drink about 2.2 litres (about 9 cups) of total fluids a day

This is just a baseline, of course. If you exercise, spend time in hot or dry weather, you consume a significant amount of diuretics (caffeinated soft drinks), or your medications require additional water consumption, you may need more water. The easiest way to handle your water consumption is to stick with the baseline above and add more water whenever you feel thirsty.

How Can I Make Sure I Get Enough Water?

Presuming you’re awake for approximately 16 hours per day, you’ll have to drink between roughly 140mL and 185mL per hour. That may seem like a lot, but it isn’t much more than four to eight sips per hour (depending on how much you take in). If you always have water with you and have an easy method of refilling, you won’t have too much trouble.

Aside from remembering, many people don’t drink enough water because they don’t like the taste. Sometimes this is a problem with tap water more than water itself, so consider a water cooler for your home if you hate the taste of tap water or don’t like the negative environmental impact of bottled water. If that’s not the problem, there are many ways you can augment water’s natural flavour to help you enjoy it more. Additionally, you can eat your water as well. Fruits and vegetables have a high water content and can contribute to your daily fluid intake. Either way, keep water with you as often as possible. A refillable water bottle can help you form better hydration habits.

Can I Drink Too Much Water?

You can have too much of anything, but you’ll find it challenging to have too much water. Dr Pam explains:

In a healthy adult, the kidneys can filter and excrete 15 litres of water a day. So you are unlikely to get too much water, provided you don’t drink an enormous amount at one time. Just remember to pay attention to thirst cues, try to anticipate when activities or the weather might increase your need for water, and carry water with you always.

For most of us, too little water is more of a problem than too much. Drinking 15 litres of water each day would not only take quite some time but make you feel very uncomfortable. There are really no circumstances where you’d accidentally drink too much water, so drinking more than you need is a safer bet than drinking too little.

What Happens If I Don’t Get Enough Water?

While more water than you need is unlikely to hurt you, too little water can cause all sorts of problems. Water aids in digestion, makes your skin look healthier, helps you feel more full so you don’t overeat, keeps your kidneys healthy (so they can properly flush out toxins), and contributes to regular healthy bowel movements. You lose out on those benefits if you don’t stay hydrated. Additionally, dehydration makes you feel tired and fatigued. Dr Pam explains why:

Dehydration makes you feel tired. The right amount of water will help your heart pump your blood more effectively, and water can help your blood transport oxygen and other essential nutrients to your cells. Water also helps energize your muscles and prevents cramping. This is especially important if you find yourself tired at the gym. You should drink two cups of water about two hours before you exercise.

Water won’t just help you stay more awake and alert during the day, but also reduce fatigue during sports and exercise. While the benefits it provides are important, this is one benefit that’s especially relevant to those who work often and for long hours (especially when caffeine’s thrown into the mix).

Ultimately, you can get by without sufficient water, but you won’t feel good. While it may be tough at first to drink as much as you need, practice will help you form good hydration habits that will lead to better overall health. Getting more water throughout the day is a good opportunity to stand up and walk around so you’re not sitting or going without a break for too long. It’s no surprise that water is good for you, but the benefits of sufficient hydration are many and well worth the trouble.


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A special thanks goes out to Dr Pamila Brar for her expert contribution to this post. Dr Pam’s primary focus is internal medicine, with a wide scope of experience with everyday health including proper hydration.

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