"Eight glasses of water"

They always say “you should drink eight glasses of water a day.” Fine, but that statement is meaningless, unless they specify exactly what quantity a “glass” is. Drinking glasses in common use range in size from 4 oz. (for grapefruit juice at breakfast) to 20 oz. (for iced tea on the patio). If they’d said “eight cups of water,” at least I could think a cup is eight fluid ounces.

I take a quart (1.5 liter) bottle of Evian to work with me and polish it off in the course of the day. If the “glass” they have in mind is, say, 8 oz., they could simply say “drink a half gallon of water a day”. But that would put people off, thinking of downing all that water in one sitting. They say “eight glasses” to parcel it out through the day; I guess that sounds better psychologically.

A curious tidbit.

Most of the citations to the addage that I’ve seen talk about 8 oz. glasses. The total of 64 fluid ounces is about 1900 fluid ounces, or about 2 liters. Drink up.

Oops. That’s 1900 milliliters.

My (implied) question was: How many ounces in a “glass”? I don’t remember a “glass” as any kind of standardized unit of measurement. But if everybody agrees it’s 8 oz., then I know how much water to drink. A half gallon.

Everybody pretty much agrees that it is 8 oz.


Hmm. I wrote those as a kind of joke, but I just noticed something. Is distilled water really OK? I seem to remember some problems associated with drinking distilled water.

We talked about eight glasses of water many many times. Its not glasses of water, but glasses of fluid & it was never 8 glasses of fluid you have to drink. Cuz you get some of that fluid in the foods you eat. Search for ‘water’ here, distilled water, also extensively covered, drink it.

I searched for distilled water and I got this thread, the arc of the covenant, and cleaning your keyboard. Water returned 185 threads. Glasses water 24 threads, none which seemed relevant. Wait, I was leaving the date set–now glasses water gives 584, and distilled water gives 114. Hmm, how about eight glasses of water…no, that’s still 276 . Distilled glasses water? 17 threads. Help?

Found it. “distilled water minerals” in GQ, any date returned 8 threads, including Is distilled water safe to drink?

Thanks Chronos, interesting read. I musta been asleep in February.

The water in the the town I live in is great. I’m used to Rocky Mountain water too, so was pleasantly surprised when I tasted our tap water here. I’ve lived here twelve years, and last year the state awarded us Best Water. The city manager decided to bottle the stuff and sell it at fairs as a publicity stunt. Homebrew clubs from around the area bring their bottles over to fill them up before they brew beer.

It makes it easier to drink eight glasses a day, that’s for sure.

Wow. Only 2 liters?

I drink a gallon to a gallon and a half of water a day…

I think I’d be really thirsty if I only drank 2 liters of water per day.

Commander Fortune, doesn’t that make you pee a lot?

I’ve never really compared volume, but the frequency doesn’t seem to be out of line with other people. I’ll be the first to be grateful for the fact that I have a “party” bladder. So, er, maybe… but if I do, It’s never been cause for notice or concern.

The eight glasses is just a base amount and you should increase it if you exercise or if it is hot weather. I don’t remember the formula for how much you should increase your intake in either case.

How much water you need depends on how much you lose (in pee, sweat, feces, maintenance).

One reasonable estimate is 4mL/kg/hour (for the first 10kg), 2mL/kg/hour (for the 10kg between 10-20kg) and 1cc/kg/hour thereafter.

Hence a 60kg person would need 410 + 210 + 1*40 = 2400cc/d

I will repeat a question I have asked before without getting a satisfactory answer.

How much more water should I drink per can of Coke?

As long as your kidneys are working well and you get enough calcium to prevent your bones from burning away, you can treat Coke as water despite the diuretic effect of caffiene. Thirst is a very sensitive indicator of dehydration, your blood osmolality changes by 1-2% and you know it.

Drink as much as you feel comfortable. Only in exteremely hot weather and/or with physical exhastion the intake should prophilactically be increased. A normal health organism can regulate the intake by fine working thirst feeling. That’s how humans evolved over millions of years. Dehydration is a very rare occurence. If you are doing heavy work, in heat, drik “ahead”, at least drink at the slightest feeling of thirst, do not delay. One can’t drink too much: you will pee it out, you will not burst.
About 8 glasses: it’s very impecise not only because we are all different, but also because we eat differently: soups, vegetables, fruits vs. steaks, ice cream, sandwiches… If you like coke, drink diet coke: they put so much sugar in regular coke, that a can or two of pure water is needed just to compensate for all the extra sugar.

Not water: Equal parts rum and coke. Sorry couldn’t resist.

To address the original question of how much water to drink, there is an medical journal article abstract (full text not online) available at http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9972188&dopt=Abstract which says the recommended amount of water consumption for men is 2900 mL, but 1250mL comes from foods and such. This would seem to fit with the 8oz/glass answer. Its 2200mL for women, does this change the glass size?

If the above link fails for some reason (my experience is long links fail rapidly) the article is “Water: an essential but overlooked nutrient” by SM Kleiner in Journal of the American Dietetic Assoc., 1999 Feb;99(2):200-6.

Its also possible to drink too much water, causing blood thinning. ick.

Not always!

Los Angeles Times, Monday 20 November 2000
Hard to Swallow
By BENEDICT CAREY, Times Health Writer
(I won’t provide a link since the LA Times links become invalid after a few days).

«“The notion that there is widespread dehydration has no basis in medical fact,” says Dr. Robert Alpern, dean of the medical school at the University of Texas Southwestern Medical Center in Dallas. … Furthermore, they say, the current infatuation with water as an all-purpose health potion–tonic for the skin, key to weight loss–is a blend of fashion and fiction and very little science.»

Most nutritionists have no idea where the recommendation of eight 8-ounce glasses of water originated. Some suppositions are that it’s derived from fluid intake measurements taken decades ago among hospital patients on IV. Kidney specialists agree that it’s a gross overestimate of any required minimum. «To replace daily losses of water, an average-sized adult with healthy kidneys sitting in a temperate climate needs no more than one liter of fluid, according to Jurgen Schnermann, a kidney physiologist at the National Institutes of Health. One liter is the equivalent of about four 8-ounce glasses. According to most estimates, that’s roughly the amount of water most Americans get in solid food. In short, though doctors don’t recommend it, many of us could cover our bare-minimum daily water needs without drinking anything during the day.»

You can read the article at the LA Times web site for more information, such as the dispelling of the myth that caffeinated drinks should not count towards the total of water consumed in a day.