Fact or Fiction – Is Drinking a Lot of Water Good For You?

A picture of Is Drinking A Lot Of Water Good For YouA common belief in health and fitness circles is that it is somehow good for the body to drink an excessive amount of water.

A high water intake is claimed to lead to all sorts of health benefits, such as increased fat burning, more energy, less appetite, etc.

Here, I am going to discover what the actual science has to say about this.

Is there any real benefit to drinking more water than plain old thirst commands?

Or are we just wasting our effort filling and refilling those water bottles all the time? (not to mention having to pee every hour of the day)

First of All, How Much is Too Much?

Before I continue, I should clarify what “a lot of water” means.

A lot of water” implies drinking many glasses of water per day, despite not being thirsty. People who do this often carry water bottles with them everywhere they go, and go to the bathroom to pee all the time.

There is such a thing as “too much water”, which is water intake to the extent that it becomes dangerous.

If you drink an insane amount, like in a water drinking contest (very stupid), you may go into a condition known as water intoxication, which can be deadly.

The body’s cells need a constant balance of various electrolytes (salts). When you pee and sweat, some electrolytes tend to get out along with the water.

Athletes that drink a lot of water to replace intense sweating, without replenishing the body’s salts, may dilute their body fluids. This can mess up the electrolyte balance and cause a condition known as hyponatremia, which can also be deadly.

Therefore, it is important to get in some electrolytes (salts) along with your water if you exercise intensely and sweat a lot. Some sports drinks include the necessary electrolytes to replace what is lost through sweat.

But given that you are not participating in a water drinking contest (you’re smarter than that, anyway), and that you make sure to replace massive sweating with both water and electrolytes, then drinking a lot of water is completely safe.

Water and Cognitive Function

Drinking a lot of water isn’t going to make you smarter, but there is a tiny bit of evidence to show that a mild dehydration can slightly impair mental function.

25 healthy women were dehydrated by means of either exercise or diuretics. On average, they lost a little over 1% of their body mass.

The women who were dehydrated had an increased perception of task difficulty, less focus, more symptoms of headache, and a degraded mood compared to controls (1).

Thus, it does seem like a good idea to make sure you do not get dehydrated, and take note that 1% of body mass is a very mild dehydration.

If you do feel a little blue at times, then perhaps you’re only a few glasses of water away from feeling your best again.

Water Intake and Bladder Cancer

There was one large-scale prospective study performed on 47.909 health professionals.

This study found water intake to be inversely associated with cancer of the urinary bladder, with those who drank 6 or more (1440ml+) cups per day half as likely to get bladder cancer than those drinking less than 1 cup per day (-240ml).

In fact, the authors noted that each additional cup (240ml) lowered the risk by 7% (2).

However, other studies found no protective effect against bladder cancer by drinking more water (3, 4)

Water and Colorectal Cancer

Several studies show a significant protective effect of water intake against colorectal cancer, which is both common and deadly. In fact it is the third most common cause of cancer death.

These studies show a risk reduction as high as 30-60%, but in some cases they are not statistically significant so they should be taken with a grain of salt (5, 6, 7).

Fluid Intake and Urinary Health

There is some evidence that drinking plenty of water might reduce chances of recurrence in patients who have been previously diagnosed and treated with kidney stones (8).

Water and its Effects on Satiety and Food Intake

A study of 20 young men discovered that those who consumed the greatest volume (600mL) of milk 30 minutes before a meal ate less than those who had a smaller volume (300mL).

Both volumes of milk had the same total energy content. The higher volume group was less hungry and also ate less at dinner 4 hours later (9)

Another study in 24 lean women found out that those who ate liquid food (soup) ate a lot less than those who had the same amount of food in solid form. However, eating the solid food with a glass of water on the side had no effect. (10)

An observational study of 5.783 chinese adults found that water intake was inversely associated with energy density of the diet, total energy intake and overweight status (11).

I’d like to point out, that despite water with a meal slightly increasing satiety, there is no indication that this would lead to weight loss in the long term, as there are so many other factors at play.

There is, however, a small chance that if you stay well hydrated throughout the day, you won’t feel as hungry and won’t eat as much.

If you really want to dig into the whole science behind water intake and health, then I recommend you take a look at this paper (12 – PDF).


Our bodies are 60% water and it is constantly being lost from the body, every minute of every day, through sweat, breath, urine and stool. The body doesn’t have any actual “stores” for water, like it has for body fat, and therefore it needs to be replaced all the time.

In fact, if you don’t drink water for a few days, you will die.

If you’re thirsty, water is the way to go. It is clean, calorie free, contains no additives and it’s really the only thing adult humans and pre-humans have been drinking for the last millions of years.

Elderly people may need to consciously make sure to drink water throughout the day as their brain may start to underestimate their required intake.

That being said, I do not see any reason why it would be a good idea for young, healthy people to drink a lot more water than what thirst commands. The mechanism in our brain that controls water balance is incredibly efficient.

A common recommendation is eight 8 ounce glasses of water per day (the 8×8 rule). According to the studies above, 5 glasses might be enough.

All in all, there doesn’t seem to be any reason to carry a water bottle around all day and drink so much that you have to pee all the time.

Make sure you don’t get dehydrated, drink a little bit of water throughout the day (especially with meals), but definitely increase your intake before, during and after workouts.

If you’ve got all that covered, then you have nothing to worry about.


  1. Well there’s an eye opener, I must admit I don’t go to the extremes but I am frequently knocking back water!

    Also I dont think I have ever witnessed a water drinking contest but it does sound like the stupidest ‘event’ ever. At least you can see the reasoning behind beer drinking contests, but water? Come on!

    Nice article anyway Kris,

  2. Johnny F says:

    Thanks Kris. A good article about many of the facts and myths surrounding water intake.

  3. I only drink when I’m thirsty but it still adds up to about a gallon a day and I pee all of the time. I guess I just require a lot of water.

  4. Thanks for the info! I’d like to add that the amount of our water intake should also depend on where on the planet we are located. Here in Bangladesh, where summer temperature goes as hish as 40 degree Celsius (plus humidity), 5 glasses of water is nowhere near enough!

  5. Philippa says:

    Interesting. I have tried drinking lots of water and found it made me feel sick and ill. However, I took some supplements for a while that are aimed at improving your fascia (all that connective tissue). One of the ingredients was supposed to rehydrate the tissue. I found then that I could drink lots of water and my body seemed to know what to do with it. I suspect that, as with all matters nutritional, it is more complicated than many people would have us believe.

  6. I’m with Julia; my thirst might be related to a diuretic prescribed for a medical condition — but I might also have convinced myself after watching my husband go through a kidney stone. I am moving to a less dry climate in a couple of months — it will be interesting to see if my need/desire for water changes then.

  7. I decided some time ago that water is overrated. I still drink at least 4 16 oz bottles a day. I don’t drink pop. I have 1 cup of coffee in the morning. Sometimes it seems like my body is holding onto all the water I drink and sometimes I am running to pee all day long. Sometimes it makes me more thirsty. I don’t see how it can help you lose weight unless you’re using it to replace a sugary drink. Sometimes I drink green tea. I try not to drink a whole lot of anything late in the day because I find I am waking up at night to pee.
    I am glad to see an article that says drink when you’re thirsty!!

    • wbridges says:

      Hi Jenny, I don’t think water is over rated as it isn’t rated high enough.
      Benefits of incorperating alot of alkaline water in your diet out weigh the heath problems associated with not having enough.
      Arthritis is basically dehidration of bone joint which can cause alot of pain.
      Even in back pain where we have disks to cushion.
      Drinking alot of alkaline water can help relieve the discomfort associated with arthritis,
      including raising you health level to a higher point.
      Kind regards.

  8. Is plain old water ok for before, during & after a work-out or is a sports drink better? I only work out 3 times a week right now for about an hour. I drink plain water then & then the rest of the day I drink water with lemon juice in it, which I have hear is good for you is that true?

    • I think water would be more appropriate for you than sports drinks. I don’t know about the lemon juice, at least it gives the water some flavour.

  9. My problem is I just don’t feel thirsty that often. I drink because I know I should. I shoot for 3 bottles of water a day, but it is often two and sometimes just one. I’m not very active though. When I am more active I do feel thirsty.

  10. Does decaf tea or coffee count as water?

  11. Michael says:

    All propaganda I believe. Bottled water is big business, makes sense to push drinking loads of water on you to consume more. As you say the thirst mechanism works, and you should trust it more often than not.

  12. I’m showing my age here but I can recall back in my Army days in the 70s when the yard glass of ale was customary initiation for anyone newly promoted. At one event a team competition was organized but the ale was replaced with water. It took the teams longer to down the water than ale so perhaps there was a message in that one for your researchers. Anyways I’ve never been a fan for water unless it’s from a fountain and don’t subscribe to that old 8 glasses a day rule. Plain water in a glass with a dash of lime juice together with some salted cashews takes care of the electrolytes. For those trying to lose weight starting dinner with a glass of milk or bowl of soup is definitely a good move.

  13. Prateek says:

    Personally, water has been helpful for me whenever i get tired. I get tired every 2.5 hours or so, if I am not doing strenuous phy activity, and I think water-intake could be regulated within that frequency. That being said, when I am doing my daily jogging, water acts as a great motivator every 1 km of jogging, around every 15 mins…Calculating all of the above, including the fact that i drink at least 2 glasses of water per meal, I easily consume at least 10 glasses of water per day!!!

  14. Hey Kris,

    I’m a big fan of your blog. First time poster.
    What’s opinion are these:
    #1. if you are only drinking when your thirsty, then you are allowing your body to become dehydrated. Since you generally are only feel thirst when you are already in the dehydrated state.
    #2. What about people that live in very hot dry climates, such as Las Vegas. I lived there for 2 years, and you don’t even know when you are perspiring because it evaporates instantly as it comes out of your pores. Many people who don’t know better, walk the strip for a few hours, then drop to their knees because they are massively lightheaded and dehydrated.

    So maybe self regulating is always a bad idea. Also helps people from snacking.

    Take care

    • Hello Kelly, thanks for the comment.

      #1 – I think your thirst mechanism should kick in before you become so dehydrated that it affects your bodily functions.

      #2 – I definitely agree, those who live in hot climates do need to drink more water to replace the sweat. I did mention at the bottom of the article that elderly folks might need to consciously drink more water as they might underestimate their requirement. Is this happening to young people over there as well?

    • Barry Bridges says:

      Hi Kelly, you were saying that you don’t know you are sweating, because it evaporates. Must be very low humidity there. I live in north Queensland, Australia & the average all year round humidity is between 85-95%. And believe me, when you sweat, you stay wet:-(

      • The West coast of NA is a dry climate. You can wear a suit in the middle of summer in Nevada/Arizona and not sweat. East coast of the US is the opposite, you can break a sweat (stay wet) just walking in from the parking lot (aka Florida in July)
        That’s Canadians retreat from Florida in April, it just becomes too unbearable.
        Vegas/Palm Springs weather I love, even when gets upwards of 40(100 F), especially at night.

        North American’s are very addicted to coffee (Starbucks)(dunkin donuts) and many folks drink only coffee and diet sodas (zero water).
        Many folks think the US and Canada are very similar countries, even one and the same. But the contrast in eating and drinking habits is huge.
        Whatever it takes to convince people to drink more water, I’m a firm believer in. Extra trips to restroom shouldn’t be a concern, staying hydrated is a very good thing.


  15. Hi Kris, does water in tea and coffee count towards part of your 5 glasses per day quota? i drink a lot of diluted orange as i find water to be very bland on its own, the diluted juice i use is very low in sugar, just wondering what u think of drinking diluted juice instead of plain water? Also so many people told me water is vital for skin health, so if u don’t want to look old before your time u should drink tons of water (prevents wrinkles and premature aging), and also the fluoride in the water is beneficial to our teeth, preventing tooth decay, i would love to hear your take on this Kris. Thanks, Irene

    • I’d say all fluid you drink counts towards your quota. I don’t really buy into the whole fluoride thing, it doesn’t seem right to me to forcefully medicate people.

  16. I’ve heard, and go by, a water drinking rule. You take the amount of pounds you weigh, divide that in half, and that number is the number of ounces you should drink during the day. So, if a person weighs, say, 150 pounds, half of that is 75. that person would need to drink 75 ounces of water each day.

    Currently I strive for somewhere between 100-120oz because I am a nursing mom and figure my toddler gets about 30-40 ounces of my water intake.

    • Not all rules apply to all people. If water helped with weight loss I would be very skinny. It doesn’t do anything for me when it comes to snacking either. I drink at least 35 -40 oz in the am when I work out.
      I do notice on weekends I don’t drink as much. At work at my desk … I drink much more.
      I always thought sports drinks were full of sugar too.

  17. Barry Bridges says:

    Hi Kris, I was i the army reserve for a while as a field medic. One thing we were encouraged to do, is to have approx 1 litre,(4 cups) of water before breakfast, not neccesarilly all at once. By the end of the day we probably had anywhere between 2-3 litres of water in one day. Now days, because I’m not in the reserve, I drink roughly 2 litres a day. Hey guys, if you drink coffee or alcoholic drinks. These dehydrate you, so you will need to drink more water.

  18. Hi Kris, i love coconut milk, i have a tin of coconut milk everyday, is it true that this is rich in electrolytes? and do u consider it to be a healty drink / food? Thanks, Irene

  19. Hi – first time poster, but have been enjoying your forum and articles for a few months now.
    ‘Enough’ water would be a very personal thing, affected by diet, exercise, climate, general health.
    I found your opening, “A common belief in health and fitness circles is that it is somehow good for the body to drink an excessive amount of water”, to be misleading. Definitions of ‘excessive’ include ‘too much’, ‘extreme’ and ‘unwarranted’. Are you sure this is a common belief? I have read of many experts suggesting people get ‘enough’ water. ANYTHING in excess is not good for you.

    I find that if I do not drink water more often than when I am just thirsty, I have difficulty with my regular blood donation. Even slight dehydration (meaning I do not perceive being dehydrated as I am not thirsty) can cause a problem for me. So I usually increase the amount of water I drink several days before I am due to donate.

    Our family believes dehydration caused periodic mental deterioration to the point of delusions in my 92 year-old father-in-law — while he was on an extended care ward! I’m sure the staff just believed it due solely to his advanced age.

    I love coffee, but I try to make sure I am not getting more coffee than water during the day. Several cups of water do not send me scurrying to the bathroom the way the caffeine in one cup of coffee will — especially if I am sitting instead of moving around.

    • Hello Barb, thanks for the comment.

      I’ve seen recommendations as high as 2 gallons (about 8L) per day which is definitely something I would classify as excessive.

      • Barry Bridges says:

        Wow, 8 litres. I think some people who have such an intake of fluids may have an under lying condition, like diabetes. Hope I didn’t frighten anyone. :-)

  20. I’ve heard that sometimes when we think our brain is telling us we’re hungry that we’re really thirsty. I don’t know if this is actually true, but it does work sometimes. If I think I’m feeling hungry too soon after a meal, I’ll drink about a cup of water, and sometimes the message that I’m hungry shuts off. But sometimes I still feel hungry. Since I live in Texas, the extra cup of water was probably a good idea anyways. As for coffee and tea, I drink decaf. or caffeine free varieties; like Korean tea made from roasted corn.

  21. My physician said that all liquids count as hydration, not just plain water. It is hard to figure out what to drink when we are looking for sugar free and low calorie drinks. I am drinking teas, coffee, my homemade lemonade made with some splenda, and some carbonated waters, but have cut out diet soda. As for me, I believe that all alcoholic beverages are basic poison, including wine. For the benefits of wine’s resveratrol, how about eating grapes? It doesn’t have the alcohol.

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