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>The well-known “8 x 8” rule — you should drink eight 8-ounce glasses of water a day — is not only daunting, it’s unfounded. In fact, nobody is sure where the idea came from, and science doesn’t support it. “It has no basis in fact,” says Michael Farrell, a professor at Monash University in Australia, who studies how the brain responds to thirst and other sensations.

> The average adult woman should consume about 11.4 cups of fluid per day (a cup equals 8 ounces) and men should consume 15.6 [...] Subtracting the 20% of water consumed through food, that means the average woman should drink about 9.1 cups of fluid daily, and a man should drink about 12.5.

8 times 8 ounces per day of fluid is 64 ounces of fluid per day, whereas ~9 cups per day of fluid times 8 ounces/cup is ~72 ounces of fluid per day. So isn't the recommendation actually _more_ than the 8x8 adage?

Sure sounds like the "8x8" recommendation (why not just say "half a gallon" or "2 liters"?) is actually a reasonable lower bound for what people should be drinking then.
Except it's well known that that is way too much water unless you are sweating a lot. If you drink that much, you'll just pee a lot, it won't actually do anything useful.

Since the article got something so basic wrong (and if it was intentional you would think they would mention that the numbers were similar), I decided to stop reading the article at that point, I don't need incorrect information.

Maybe it's an editing mistake?

The actual amount of water you need varies by exertion, and diet and all sorts of things, it's not a fixed amount.

Yes agreed, it's not helpful to search for a constant consumption requirement. A healthy and sedentary person, with a reasonable diet, on a cold, gray, damp day, does not need to consume much water.
>The actual amount of water you need varies by exertion, and diet and all sorts of things, it's not a fixed amount.

I completely agree with this statement.

>If you drink that much, you'll just pee a lot, it won't actually do anything useful.

I drink on average 6L of water a day. When I first started water-only fasting I was urinating constantly. I discovered that this was because I would drink a lot in one sitting, (as a 'meal' replica) and then interspersed throughout the day.

Once I changed my consumption style to ~150mL frequently I found that my body used the water better. Once it realized that a "constant supply" was readily available (and didn't need to worry about feast/famine cycles) I retained what I needed and more casually urinated the processed water.

My body can better manage itself when I drink 150ml 40x a day then it can manage 1L 6x a day.

If the body was previously worried about "feast/famine" of water before, wouldn't it retain water rather than pee it all out?
The body doesn't really have any way to retain [liquid] water without causing medical issues. There's no storage compartment except for fat that could be metabolized into water.

You can also store water, for a short time, mixed into fiber in food that was recently eaten.

But drunk more gradually thorugh the day, it is able to be 'retained'?

Asking in good faith, taken independently each of your comments make perfect sense to me!

I'm not implying I have 'water pouches' or anything as silly. 1.5L of water in my stomach gets processed as quickly as my kidneys can manage. Thus I urinate out a large % of that liquid intake before use can be made of it.

Continually drinking small amounts doesn't overwhelm my stomach and therefore it feels like I urinate less, and 'retain' that water.

Wow, 6 liters? you drink 40 times a day?

(24h - 8h) * 60 min/h / 40 = 24 min

So you stop what you're doing every half an hour and drink get a glass of water and drink it? Or do you have constant supply at your desk or how are the logistics?

I have a 1.5L Naglene bottle at my desk, and a water cooler 10 feet away in front of the server-room doors.

So cold water is always close.

I also drink when I'm at home.

I don't understand why you're downvoted. At the very least, the article is inconsistent on this point:

8 cups / day is widely reported - and suggested in the article itself - to be too high as a minimum, and yet the article actually ends up concluding that you need to be drinking more than that.

What people often take away from that is that they should drink eight glasses of water _in addition to_ everything else they might consume--soda, juice, coffee, and anything else that has water in it. And they think there's a rule they need to adhere to, and not trust the fact that our bodies are actually pretty good at letting us know when we need water.
>soda, juice, coffee

Don't consume these. They have the opposite effect of dehydrating you.

If these have a dehydrating effect, it will be (literally) drowned out by the amount of water consumed. It will be a vast net-positive.
I guess you use the same logic when drinking sea water.

Sugar and caffeine will dehydrate you. You'll be driven to drink more water to compensate.

Vote me down, obese soda patrons.

Sea water is very salty, and will box your kidneys in. It's not the same at all.
Not what I was getting at, at all. The sodium content will make you drink more water to compensate.
You're misinformed. Caffeine does not dehydrate those who consume it regularly.

Sugar can dehydrate you if you are diabetic or have other blood sugar regulation issues. You're playing straw man games.

Caffeine is a diuretic.
Surely that only means coffee + water is not as good at hydrating you as plain water, not that it actively dehydrates you.
It has a mild diuretic effect on nonregular users, yes.
About the only thing people are likely to drink in liquid form where you lose more than you take in is alcohol.

Most people shouldn't be taking in refined sugars more than a couple times a month. That's a somewhat separate issue. There are of course other factors at play, but that has less to do with hydration and more to do with nutrition and disease.

Being an asshole won't really help your position. I tend to be snarky myself at times, but misinformation+snark == downvotes to oblivion.

I was always told that when growing up but I never understood how drinking soda would actually cause a net loss of fluids. A quick search shows that my suspicions were correct. Even though drinking soda doesn't hydrate you as much as drinking water, it does not dehydrate you.

https://duckduckgo.com/?q=does+soda+dehydrate+you&ia=web

If that were true, we'd have mass dehydration deaths on the daily.
You would need to drink a massive amount for it to be lethal.

Instead what you see are obese individuals because drinking soda has the net effect of making you more thirsty, causing people to drink more soda. Which is exactly what the soda makers want you to do, and will fund studies to make you believe otherwise.

If you truly believe that these will net-dehydrate you, it should be pretty easy to prove - just survive for 1 week drinking only soda/juice/coffee. If you die of dehydration, we'll admit you were right :)
I can confidently admit that when I was a stupid teenager, I had consisted on Soda & Coffee and potentially only getting raw water content absorbed from foods for multiple weeks on end.
I've survived for years drinking mostly iced tea, with a soda in the morning instead of coffee. I can count the number of times I drink plain water in a week on one hand (after exercise, basically)
> bodies are actually pretty good at letting us know when we need water.

My body certainly isn't.

Then you need to see a doctor about that.
What kind of psycho drinks water by the 8 fl. oz. glass?
I had to look up what 8 fl oz is in a sane unit(236ml), and that seems perfectly normal to me - pretty much all glasses that you can buy here are 250ml. If you buy a 330ml can of coke you can usually pour most of it in with some left for a top-up.
I wouldn't call anyone a 'psycho' for not adhering, but personally I'd typically pour a pint (568ml) of water, at home.

Of course, at any restaurant glasses given with water for the table are going to be somewhere much nearer your 236ml, so there's really nothing psychotic about it.

> Of course, at any restaurant glasses given with water for the table are going to be somewhere much nearer your 236ml, so there's really nothing psychotic about it.

Bingo. It's not hard to sip on a average sized glass of water during a meal. I routinely kill a 750ml water bottle at the gym or when hiking.

It could have from Dr. Benjamin Batmanghelidj, author of Your Body's Many Cries for Water in which he claims that chronic dehydration is the source of most disease (and thus water is the cure). The 8x8 was a minimum threshold for his water treatment protocol as I recall. According to Dr. Batmanghelidj, feeling thirsty was not reliable as an indicator of need for water, as dehydration was more likely to manifest as pain or hunger than a feeling of thirst. His methods have been called into question. however.
Potential controversial opinion but what could really be wrong with: “When you’re hungry eat, when you’re thirsty, drink”.

Sorry but they just seem like such automatic functions I don’t see how it needs to be complicated any further.

Oftentimes what you think is hunger is thirst.

Babies who have stomach trouble sometimes over-eat because they mistake stomach pain for hunger.

So instinct/reactions aren't failsafe. Especially when we've loaded our diet with addicting things.

> Oftentimes what you think is hunger is thirst.

Anecdotally, often my thirst is disguised as looking for something to snack on that will cause me to salivate, like chocolate.

When I make a conscious decision to have a big glass of water or two, the craving goes away.

"Hunger" is more a function of time than a function of need, for one thing.
It is a variadic function of unlimited number of variables. :)
I' am pretty sure my meter is broke, I don't feel thirsty at all and have to consciously keep track of my "thirst".

To the point of not being able to sleep for a good part of 2018 due to severe pain, I couldn't lie down in any position or my body would ache terribly. It only got fixed after my wife asked me how much water I drink during the day, I had to think about it and my response was baffling even to me "ehr... one glass?". The sleep issues went away after a couple of days drinking more water.

Is anything weird going on with your serotonin levels? Genetic mutations? Antidepressants?
I seem to get dehydrated quite frequently as well. I simply forget to drink water and rarely do I get the thirsty feeling.
A good way I found to gain more sensitivity on whether i'm thirsty or hungry is to separate the two during meal times. When I have breakfast or lunch, I don't drink any water or juice, unless i'm having trouble getting it down my throat. I either do it half an hour before or after. I've been doing this for years now and now I can accurately feel when i'm truly thirsty or hungry. shrugs try it..
> unless i'm having trouble getting it down my throat.

If you have to get that far, are you certain to do the best job for your health?

Along those lines you could say “when you want something sweet eat something sweet” but that wouldn’t be good for your long term health.
But many people prefer routine and automation. Routine helps avoid wasting time and mental efforts by staying alerted to how exactly you feel at all times, not to mention the ease to misread your feeling.

I can only speak for myself, and find it really challenging to reliably evaluate my hungriness/thirstiness. If I can get hungry just by looking at food, or if I end up eating way too much because I've thought I was hungry (I wasn't!), then how on Earth can I possibly rely on such elusive indicators?

> Potential controversial opinion but what could really be wrong with: “When you’re hungry eat, when you’re thirsty, drink”.

That's how I got really fat.

The pop science consensus has been that the human evolved for a world of food scarcity, and when confronted with an unlimited supply of food, that system breaks down. That seems pretty plausible to me, looking at global obesity rates.

I am sure bamboozled meant it as a lower boundary.

In my opinion it works with food for almost all people and with fluids for many. I also drink more than enough just be drinking when I am thirsty. Some friends and also commenters here mention that their thirst doesn't work as well. So key is to know whether you can rely on your thirst.

>Potential controversial opinion but what could really be wrong with: “When you’re hungry eat, when you’re thirsty, drink

People forget to hydrate all the time, and can ignore their thirsty signals, or even not feel thirsty...

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It's possible that until very recently we didn't have that much salt in our food, and so we didn't have time to evolve a proper response to that. And by "very recently" I mean a mere 200-300 years ago. Consider that in many cultures spilling salt is considered a bad omen, that most likely means salt was scarce not long ago.
Water + electrolyte imbalance are pretty big together. Unfortunately, people have been told to reduce salt, drink more water... etc. combined with refined, heavily processed foods. Confounded by the fact that too little of one electrolyte has similar symptoms to too much of others.

Most people don't even understand how to listen to their own bodies anymore, and doctors are more concerned with prescriptions that treating underlying issues.

> Most people don't even understand how to listen to their own bodies anymore, and doctors are more concerned with prescriptions that treating underlying issues.

Well said! It is the sad truth that doctors can be coerced by private companies into personal monetary benefits from selling their products.

The pop-sci wisdom is that what you get from the hypothalamus is a generalized primal desire. It may be triggered by thirst, but you experience it as a longing for food, sex, or sleep instead. Sometimes all of the above.

When you feel like this, you can recognize that thirst is also a likely explanation, and reach for water quickly and cheaply as a debugging step. At least rule it out before making tradeoffs to placate more expensive needs.

The distinction is between “8x8 glasses of water, independent of all other fluids you ingest” pseudoscientific rule, and “9.1 - 12.5 glasses of non-alcoholic fluids, which includes juice, milk, coffee, tea, etc, not just water”

Drink 6 cups of coffee, a glass of OJ, and 2 glasses of water would be just fine for an adult Woman, but the “rule” convinces people they’re still falling 6 glasses short of water.

Six cups of coffee?! I think you might have other problems.
Your body gets used to it and it basically feels one cup of weak coffee followed by five cups of water.
Well the first one is drinking straight water 8 ounces of water 8 times a day and the second statement is you need to drink that many ounces of fluid regardless of source. That includes the foods you eat and any liquids you drink. I think even the diuretics are included in that second figure.
Subtracting the 20% of water consumed through food
It would be so nice to not only give measures in freedom units...
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If only there was a large corpus of searchable knowledge only a click away where the conversions could be determined.
Turning a 5 minute read into a 10 minute one.
It takes you as long to read the article as it does to google a simple conversion?
You have to do it multiple times since there is more than one value. Also include time for switching tabs etc, and then returning and working out where you were.
Multiply this by every single person who has to do this whole process.
FWIW if you're on a Mac, Spotlight will do simple unit conversions, so you can just cmd-space and do it in the popup without having to leave the page.

That said yeah US units are absolutely brain-dead and confusing, how hard is it to put real units in parenthesis?

Was having the same problem, then wondered: aren't their browser extensions which parse the text and convert units? Did a quick search but didn't find any - shouldn't be that hard though?
There's AutoConvert and EverythingMetric for Chrome. The automatic conversion is sometimes a bit annoying as there are edge cases.
Absolutely, and, living in the US, I can tell you a lot of mineral water bottles are packaged in metric units (1 or 1.5L bottles).
What would be the use? These are just rough guidelines.
Am I the only one who is rarely, if ever, thirsty? I couldn't drink 8x8 even if my life depended on it.
Me and my sister are similar. There used to be a time when my only water intake was 1.black coffee in the morning. 2. green tea in the evening. I have had to consciously create a habit of drinking more. My current metric ( to avoid kidney problems ) is to keep the pee as white as possible ( I have no scientific backing for this ).
edit: There you go, Causality's comments says otherwise about the urine.
Better have clear urine than dehydration though. You have to try really hard before drinking too much water becomes a problem.
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> keep the pee as white as possible

That's a symptom of overhydration. Pee should be yellow, as everybody knows.

If you're getting a lot of water from your diet (e.g. fruits), you're probably less thirsty than someone who eats a lot of dry sugary/salty foods.
It could also be that you are not used to it. I have periods where I don’t drink much and then I am not thirsty. As soon as I force myself to drink more I also feel thirsty more. If you are not used to drinking it’s also easy to confuse being thirsty with being hungry.
I used to be like this. Rarely drank water actually, mostly drank soda. Moved to Arizona, even in the winter I _always_ carry a large water bottle around with me. I don't keep track, but I'd be willing to bet I drink a fair amount over 8x8 without thinking about it. Climate, anecdotally, plays a large part, which makes sense to me.
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If we spent a night at a bar how many drinks would you have? Might not apply to you but I've spoken to many people that think it's hard to drink 3L of water but will happily not back 6 pints (500ml) in an afternoon.
>When urine turns yellow, and especially if it becomes dark, dehydration has begun.

Misinformation. Light yellow urine does not mean you are dehydrated and crystal-clear urine is not a "hydration goal".

The problem is, essentially the only thing anyone agrees on when it comes to "how much" is "its different for everyone".

So what's not different for everyone? Well, if your pee is dark, then you're probably dehydrated. Ok; now we have a useful signal. It's not perfect. It doesn't capture the subtleties of the entire situation. But it's USEFUL.

Exactly. Vitamins can discolor urine no matter your hydration level.
What is ounce ?
Drink when you are thirsty.

Really, unless you have a rare and diagnosed medical condition that says otherwise, drink when you are thirsty.

> Subtracting the 20% of water consumed through food

Where does this article get that number?

Edit:

Ok, it gets the number from the above link.

I still really don’t trust this article as a source of info about how much water to drink. And anyway it ends with “mostly drink when you are thirsty.”

>Drink when you are thirsty.

Yep, and don't wait if you're thirsty. Learned my lesson on that one with a couple kidney stones, and never again.

Your post just made me chug a glass of water. Having seen many people go through it (most of my family as well), I am terrified of stones and drink a lot of water and thus pee annoyingly often. Staying in the lane between stones and water intoxication is a hassle.
> Staying in the lane between stones and water intoxication is a hassle.

It's a really, really wide lane. If you're drinking that much water for fear of kidney stones, you may want to address your anxiety/compulsivity as well as your risk factors for kidney stones.

Having passed a few stones, I like to say that they make my legs tired. I now drink a lot of water and make many trips to the restroom.
> ... according to a widely cited 2004 report from the Health and Medicine Division of the National Academies. People get about 20% of their water from food, the report states.

It gets the number from that report, which is just above your quote. The article contains a link to the report: http://www.nationalacademies.org/hmd/Reports/2004/Dietary-Re.... Maybe the link was added later, but the article includes its source

My body only tells me I am thirsty when I am already dehydrated.

I'd go to the toilet, notice my urine is dark from dehydration, go on with my day and then only later get thirsty.

Now that I force myself to bring a big water bottle at work and finish it before going home, I never feel thirst.

It probably depends on your body's quirks but telling people to drink only when feeling thirst and not before seems dangerous to me.

Keep a water bottle at your desk. You might find yourself mindlessly drinking from it more than you'd expect, whereas if you had to go someplace to get water, you might be more inclined to ignore the thirst.
As said above, that's what I do. I drink it through the day but that's a conscious choice and not something my body tells me to. If I waited to be thirsty, I would only drink before bed.
It seems like the argument is for "what is the minimum amount of water needed", but I wonder if it's still better to consciously drink more water? Could it be good for helping the body detoxify itself? I've heard drinking more water is a "beauty tip". Also drinking more water could satisfy the signals that you may interpret as hunger instead of thirst, which could promote weight loss, or maintaining a healthy weight. As the article points out there's a toxicity level of too much water, but I'd like to know what the optimal amount to drink is. Maybe that's where the 8x8 rule comes from?
Air Force Survival School Instructor: "Drink up! By the time you feel thirsty it's already too late!"

Me: "Not when you're making me carry around 40 lbs of water in canteens on my belt."

This is bad advice. Kidney stones are a common disease not requiring diagnosis that indicates you aren't drinking enough water.
What is now also known, and not very clear from the article, is that sipping water throughout the day is not very good.

As the article is pointing out, a lot is happening when you drink water. And sipping all day means the body never gets rest from the 'water intake mode'.

So it is best to drink water until you have enough when you feel thirsty.

Edit: this was studied by Thomas D'havé, Leo Pruimboom, Tim Noakes, and others

I think it's not very clear from the article because the article doesn't claim that sipping water throughout the day isn't very good, just that it doesn't cause some neurons to fire.

Do you have any source for "sipping water throughout the day is not very good" and "sipping all day means the body never gets rest from the 'water intake mode'"?

Source? This seems just as unsubstantiated as the article.
"water intake mode" The body is not known to have such a mode unless you are referring to literally having your mouth open while you pour water into it.

I suppose next you will tell me that constantly breathing is harmful because it means that the body never gets rest from air intake mode.

Water intake is regulated by homeostasis... you should drink as much as you want to drink.
But not that much you water-poison yourself!
You can over-hydrate though. The myth that you need tons and tons of water has actually led to over-hydration which can cause serious problems or even death. https://en.wikipedia.org/wiki/Water_intoxication
Sure, you can over-hydrate, but when is the last time someone died from drinking too much water who hadn't also just run a marathon? Referring to a normal person who decided to up their water intake, and died later that day?
> The myth that you need tons and tons of water has actually led to over-hydration

Absolutely false. Do you have any evidence for that statement?

yea, this is totally true. You dilute your electrolytes and get hyponatremia. Very common in marathons now - here's a paper on it: https://www.nejm.org/doi/full/10.1056/nejmoa043901

"On univariate analyses, hyponatremia was associated with substantial weight gain, consumption of more than 3 liters of fluids during the race, consumption of fluids every mile"

Came in to post this.. just drink whenever you feel to.
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If you're a Chrome user, an incognito window also does the trick.
Firefox and Safari have incognito modes, too. Call them something different ("new private window" is the menu label, in both cases) but they're the same thing, more or less. Not sure about Edge. Probably has one too.
>Firefox and Safari have incognito modes, too. Call them something different ("new private window" is the menu label, in both cases) but they're the same thing

If anything, chrome is the one that's different.

chrome: incognito

firefox: private

safari: private

edge/internet explorer: inprivate

I live in the mountains in Central Arizona. I sometimes hike with a retired surgeon and he recommends one liter an hour, maybe slightly less in the winter when it is cold and you don’t sweat as much while hiking. Anyway a liter an hour sounds reasonable. I just got back from a two hour hike with friends and that is what I consumed.
Having done some winter camping I'd recommend not cutting your water intake much in the winter. The air is usually dryer and you lose more water from breathing than you do during the summer. Because you aren't sweating as much it's easy to forget this and get dehydrated.
Body weight (lb) divide by 2 seems to be the consensus general number of ounces I've seen from people like Dr Rhonda Patrick. And the more physically active you are, the more you should drink.

Eg: A 200lb person should drink 100oz+ of water a day.

In metric units: a 90kg person should drink about 3L of water a day.
Thank you for SI units. Some of us not living in the great country run by the universal moron understand this now better.
How did our predecessors drink before pottery was invented? You just cannot stay for all time close to a source of water, right? I suggest a kind of fruits/veggies might be a better source of water especially when you move.
Waterskins made from animal hide
Which is a newer invention than pottery.
Look at old maps. Every village is either next to a river, next to a lake or centered around a well. People didn't leave their communities for many reasons but one of them was because you needed water.

Wooden buckets, waterskins and berries are indeed the solution. Indigenous people of the Great Plains and Canadian Prairies used buffalo intestines and stomach to make waterskins and travel the plains.

Fruits are also sources of fructose, especially fruit juices. Veggies juices are supposed to be healthy indeed.

But eating raw... what numbers of fruit/veggies you need to cover the same amount of water?

I just do a pee-drink-work-[repeat] state machine. works out well for weekdays.
I only drink water during/after lawn work. That amounts to maybe 32oz. Other "water" would include the half gallon or so of green tea I drink daily, along with my 4-5 double espressos during working hours.
when I am doing intermittent fasting (20/4), I drink about 120 - 150 ounces a day. It's not uncommon from what I see in the IF subreddit.
Left to my own, I'll drink between 32oz to 64oz per day. However, a few years ago, I did a several month stint of attempting 1 gallon a day (128oz, or 3.79 liters). It was actually challenging. What I did notice is my skin cleared up and my acne breakouts became nearly non-existent. I had to ensure I stopped drinking before around 4pm otherwise I would be up all night having to piss.
Try skipping a meal and drinking water to satisfy your hunger. I wonder if many of us have confused the body signals for "eat" and "drink water" since we can get water through eating, but also the pleasure and enjoyment of the food itself.
For sure. We've done that with our kids. "<whining>I'm hungry</whining>." "When did you last drink water? Go have a cup of water and let me know in 15 minutes if you're still hungry."
I find pickles to be a great combination of the two since they are mostly water, but with a flavor and texture I quite enjoy.
Absolutely. "Hungry" and "tired" are two signals that are often confused as well. Try just going to sleep if you're hungry late in the day!
Drink water when you're thirsty. If you don't know when you're thirsty, you have bigger problems.
People who eat more "living" foods such as veggies and fruits consume water via those foods. Also, dehydrating foods such as dried, salty potato chips affect this too.

So the foods you eat drastically affect how much water you need. Lastly, exercise plays a big role as well.

> "living" foods such as veggies and fruits

What is a non-living food? (Given that by living here we clearly mean 'has lived'.)

I imagine they mean food that was still alive either while you were consuming it or when you cooked it.
/r/hydrohomies would like to have a word with you..
the answer is: "IT DEPENDS", on dozens of factors, starting with your environmental heat & humidity, and current workload.

Generally, drink at least enough so that you pee clear once a day, and not too dark. If it is clear all the time, you may have other issues. Also, roughly follow your thirst (unless you are drinking sweetened / salted drinks).

Is there a metric version of this article using simple measurements like liters instead of cups, quarts, gallons and other weird things?
> simple

Hm, you spell 'logical' in a weird way :-)

It should be noted that human infants don't drink a drop of water for the first 6 months of life.
Human infants also don't eat (what is considered for adults) a healthy diet or get any exercise. We shouldn't be taking health advice from infants' habits.
anecdata: if I feel myself getting ill, I drink more water. Before I did this, I became ill more often.
I thought that was widely understood and common knowledge. If you're approaching or already suffering from a flu or cold you should drink a lot.
A key point the article mentioned is that you can tell if you are well hydrated by seeing if your urine is reasonably clear. Though I would guess if you are exercising or in real hot weather you would need to stay ahead of the game by drinking more than needed for that.
Are you thirsty? Try drinking some water.