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

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.

Cheers Lifehacker

Got your own question you want to put to Lifehacker? Send it using our contact tab on the right.

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.


      • This whole conversation is just so stupid. You don’t need to read 10 paragraphs about drinking water. If you feel like you want a drink, have one.

        What’s next: “How do I know if I am peeing enough?” – “How do I know if I am breathing enough?”

      • I hear that from time to time, but I gotta call BS on it. Does it really make sense that evolution (or God, if you’re in to that kind of thing) would produce a creature who only get’s thirsty when (s)he’s already dehydrated? That’s like only getting hungry when you’re in a famine.

        • As creatures aren’t that elaborate. The feeling of being thirsty is a physical phenomenon that occurs when you begin getting dehydrated. Yes when you feel first it’s probably only low levels of dehydration, but it’s still dehydration none the less. As an example though a good way to think of it might be that the feeling on thirst maybe comes from something such as your throat becoming dry, or something like that which is a direct result of not being properly hydrated.

          • That’s bending the meaning of the word “dehydration” though, isn’t it? It’s like saying “When feel a little chilled, you’re already hypothermic!”. The implication of “if you’re thirsty, you’re already dehydrated” is that if you’re thirsty, it’s too late and you’ve already started causing damage. That’s where I’m calling “BS”.

            A more accurate saying should be “If you’re thirsty, you body is indicating it’s just starting on the road towards dehydration”

          • i drink around 2-3 ltrs per day as I’m always thirsty. It drives me nuts, I walk 25minutes to work, I’m thirsty, I sit at my computer, I’m thirsty.

  • 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
    Absolute bunkum…….. Infact this has been discussed either here or Giz in the past and that time they had a completely different figure. If I drank three litres of water a day I wouldn’t stop pissing all day. Drink when you are thirsty, don’t try and force your body to do otherwise. The only time I will drink when I don’t feel thirsty is when I feel my lips are getting dehydrated and that very seldom happens. This isn’t the first time Dachis has gotten it completely wrong. Here’s just one example of the correct way to look at it, there are more if you look.

    • You’re right. According to other articles published on this very site, we get some/most of our water in the food we eat. We don’t actually need to sit down with 3 litres of water and drink it.

    • I read that article on the Age when it came out and have my doubts. There seems to be a lot of “experts” claiming very different things when it comes to water consumption. I think it can be somewhat a personal thing. I drink around 3L per day, don’t need to piss more than every few hours, find that I function better than when I use to go the drink when I’m thirsty route, but that’s what works for me, everyones different.

    • There’s also this:

      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.

      While generally true, there is actually something called water poisoning. Yes, it’s actually a thing. You can get seriously sick and potentially die from drinking too much water, just like what happens if you drink too much alcohol. Admittedly, you need to drink a LOT of water for that to happen, but it still can.

  • I have been told by a bladder and continence expert that 30mls/kg/day is recommended.
    This means that :
    50kg =1.5L/day
    60kg = 1.8L/day
    70kg = 2.1L/day
    80kg = 2.4L/day
    90kg = 2.7L/day
    100kg = 3L/day

    I had a look approximately 1 year ago for studies looking at how much fluid people should actually drink in a day. There are a lot of recommendations out there but little in the way of actual studies that have been done. Then of course there is the old ‘8 cups’ suggestion that has propgated well, despite any real evidence for its suggestion (think about it, does a 40kg person need the same amount of water as someone who is 140kgs)

    You need to take into account if you are exercising or if it is a hot day as well as you will require more fluids under these circumstances. Some people are also on fluid restrictions and this too must be taken into account.

    Hyperhydration (too much water) is certainly possible, and death can occur, especially if you are extremely dehydrated, as too much water can lead to hydrocephalus (water on the brain).

    One should also consider that alcohol has a diuretic effect on your body (encourages your body to loose fluid – a significant reason for hangovers!). Current guidelines are to have only 2 standard drinks a day and a maximum of 4 standard drinks on any one occasion (note that this refers to a standard drink, not one beer which is often 1.3-1.5 standard drinks).

    One should also consider not to take more than 50% of their daily fluid intake as caffeine due to effects on sleep, bladder irritation and being a weak diuretic as well (this includes caffeinated tea, coffee and some soft drinks such as coke).

    One should also try and limit sugar intake, of which there is quite a lot in soft drinks, cordial, juice, and of course adding sugar to tea and coffee, due to the increased risk of weight gain, diabetes and other chronic disease and dental caries. (holes in your teeth).

    The latest Australian dietary guidelines released by the NHMRC ( released this month are a great read.

    • Yer… I found it rather dry myself…. 🙂
      Seriously though, I couldn’t see a reference to the daily water intake recommendations, perhaps you could make a more direct link..?

  • “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.”

    Fragment, consider revising.

  • From the most reliable scientific website there is,
    If you make the rounds of health websites or actually read your mom’s email forwards before deleting them, you’ll probably have been told that you need to be drinking at least eight cups of water a day, even if you are not thirsty and have a hard time getting it down.
    As common sense might tell you, though, no, you do not need to force feed yourself water when you’re not thirsty in order to be healthy. As Scientific American reports the whole idea seems to stem from a misunderstanding of a 1945 study which recommended that amount of water for the average person. What researchers in that study understood, and people parroting their conclusions don’t, is that unless your diet consists wholly of dehydrated biscuits, food also contains water.

    (Yes, tongue in cheek – cracked is a comedy site not a scientific site. But, when they run articles like the above, they actually do very well at citing sources – and this one looks pretty legit)

  • Water intoxication can be fatal, but my (lay) understanding is that this occurs when consumption is excessive in a very short amount of time. I think, and this should be checked, that regardless of the 15L/day, the kidneys can only process up to 1L/30mins, so skulling 2L in one hit is where it starts becoming quite dangerous.

    • It’s called hyponatraemia (low sodium or salt), and it’s nasty. I’ve seen it a few times at work (in an intensive care unit). Basically when your sodium in your blood gets too low, the difference in concentration causes water to enter your bodies cells. In a confined space such such as your head, this becomes a problem as their is insufficient space for all this water.

      Obviously if you keep filling your brain cells with water, eventually the pressure in there becomes too large and reduces cranial blood flow. Symptoms include headaches, dizziness and nausea, but in severe cases can cause brain damage and death.

      • This has happened to me and I had a seizure in the street. I wasn’t even drinking an excessive amount of water, it was the fact that it had been coupled with too little food and sleep – at least that’s what the doctor told me.
        A famous case in the UK was a schoolgirl called Leah Betts who died after taking ecstasy, the broadsheets immediately blamed the drug, the inquest showed that she had died from her brain swelling after drinking 7 litres in 90 minutes.

        • There was a similar case in Australia when a 15 year old girl named Anna Wood died from the same thing.

          The one case I remember was someone who had to have a colonoscopy, and was required to drink the disgusting bowel prep stuff to clear her out before the procedure. She hated it so much, that she had a glass of water with each sip of bowel prep…too much water.

  • I’n 6’5″ and 125kg and I drink 5-8 litres a day. I have never had any problems with feeling sick/headaches ect from drinking too much. When playing footy all day in the sun I forgot to drink during the day then got dehydrated and drank 2x 4L or as the juices within 15 minutes, because I was dehydrated still felt thirsty. Apart from feeling slighly queasy and hearing and feeling the liquid moving around inside I felt fine.

    Also If I go for a brisk walk (I aver average 8.5kph I loose a kilo of sweat.
    So I think it’s very unlikely you would ever drink too much/too fast. Dehydration would be slot more likely to happen. I have had my kidneys tested to and they are in perfect condition (have to have tests due to creatine supplementing).

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