The hydration myth that will not die and the bottled water menace

Growing up in the tropics where it was always hot during the day and there were very few buildings that were air-conditioned and ceiling fans were the only cooling devices, we used to perspire a lot. But there was never tall of preemptively hydrating by having a regimen of regular water drinking. We drank when we were thirsty and that was it. So I was somewhat surprised to find people in the US obsessing over drinking water. There was a widespread belief that one should drink at least eight glasses of water a day and that coffee and tea did not count towards that total because they were dehydrating. It turns out that both those things are not true, something that researchers have been saying for some time but the message does not seem to be getting through.

One well-known recommendation suggests drinking eight glasses of water a day; another warns that if you feel thirsty, you’re already dehydrated.

But anxiety about water consumption could also stem from a different, more philosophical source: Hydration is now marketed as a cure for nearly all of life’s woes.

People hydrate as if their reputations depend on it. They dutifully carry water bottles with them wherever they go, draining and refilling them with gusto.

“There’s no evidence that a little bit of dehydration really impacts anybody’s performance,” said Dr. Mitchell Rosner, a kidney specialist at the University of Virginia who studies overhydration in athletes, in a phone interview.

He said that most recommendations for hydration come from studies of athletes, who lose fluid rapidly during workouts or competitions, and are at a much higher risk for dehydration than the average person.

For those of us who spend all day at a desk, Dr. Rosner said, it’s best to drink only when we feel thirsty.

Overhydrating, he said, isn’t helping anyone. At best, Dr. Rosner said, “You pee it out.” At worst, it can cause the sodium and electrolyte levels in your body to drop to dangerously low levels. The condition, hyponatremia, can result in hospitalization and death. (This doesn’t happen often, but … good to know.)

The tasty beverages you thought of as dehydrating, like coffee, tea and beer, are actually hydrating.

“Coffee is a hydrating beverage,” said Ms. Antonucci, the nutritionist. “If you’re drinking it, let go of the guilt. Enjoy it.”

The bottled water industry is the main beneficiary of this myth. How they managed to convince people to buy something they can get free is something I will never understand. People buy cases of it and lug it to their homes when they could so easily just open the tap and get unlimited amounts for free. Bottled water is also a menace, depleting water supplies in some areas and producing massive waste in the form of plastic bottles.


  1. says

    There was a widespread belief that one should drink at least eight glasses of water a day and that coffee and tea did not count towards that total because they were dehydrating.

    If that were true, I would have died ages ago. I do drink water every now and then, especially while traveling when water taps in public toilets provide the only free drinks I can get, but at home I prefer to drink tea or milk or just eat some foods with lots of water in them (fruit, soups).

  2. Holms says

    I seem to recall that the early study finding, that people needed eight glasses of water a day, also stated that about half iirc of that daily need is supplied by the meals we eat, as all food contains some amount of water. Meaning, a person probably only needed to pour themselves four or so glasses of water.

    It should also be pointed out that bottled water is usually just a scam with really good marketing. They almost always come from the local municipal water supply and have a label slapped on it, together with a staggering markup. They are rarely better than tapwater for purity, and sometimes worse, as some remove the beneficial fluoride before bottling.

  3. anat says

    Problems with hydration are more common in dry hot climate than in the tropics. As a child and teenager I had rather frequent headaches, as well as a tendency towards dizziness in the summer months. These went away in my early 20s when I got used to hydrating regularly. The rule is to drink until one’s urine is colorless (except for situations where the color of urine is affected by medications). Nowadays my diet is very heavy on fresh vegetables and fruit so I end up needing less water for similar levels of hydration.

  4. Ridana says

    I think part of the reason bottled water took off is that a lot of municipal and well water tastes like crap. Flint was just the extreme end product of cutbacks in water purification. I never really did get used to the water in L.A., but the water in Sacramento tasted so much better when I moved here. I also notice that it starts tasting off for a few weeks starting with the first rains of the winter, which makes me wonder how much ag runoff enters the system and isn’t getting completely filtered out. Also water quality standards keep getting relaxed with deregulatory fervor. Just because the water passes tests so it won’t necessarily kill you doesn’t mean it tastes good. Like the sulfur water at the summer camp I went to as a kid was technically safe to drink, but you had to hold your nose just to get near the tap. I could bear it for a week but people who lived in that area either had to get used to it or filter it somehow. Bottled water is another option these days.

    I wonder if L.A. water had tasted better, would that have kept Perrier and its ilk from making such an impact? Hollywood stars made it look fashionable, but would they have bothered if tap/fountain water had been delicious and refreshing instead of something you can only choke down because you’re thirsty?

  5. Teve says

    I try to stay super hydrated because kidney stones run in my family. I haven’t spent the necessary hours looking through the literature to see if there’s a strong evidence about that, but I’m not overdoing it either.

  6. says

    My country dentist told me once that he could tell who was drinking well water vs municipal flouridated water. He also said that there were “soccer moms” with crappy teeth because they were drinking unflourinated bottled water.

  7. xohjoh2n says


    It should also be pointed out that bottled water is usually just a scam with really good marketing. They almost always come from the local municipal water supply and have a label slapped on it, together with a staggering markup. They are rarely better than tapwater for purity, and sometimes worse, as some remove the beneficial fluoride before bottling.

    Or worse, they occasionally add in dangerous impurities that weren’t in the original tap water:

    (Similar to the Perrier/benzene scandal of 1990.)

  8. says

    I’m the extreme version of Andreas Avester.

    I drink maybe 1.75l of OJ a month, probably less, but 1.75l is about what they’re saying we should drink per day, so that would be 1/30th of what I’m supposed to get if the 8 glasses/day thing were true. When I’m on a road trip, I pack up about 1.5 l of tea and when that runs out I drink water. When I’m at home and not drinking OJ, I drink ice water a bit in the summer and then it’s nothing but tea and that bit of OJ for 10 months. I also drink about 8 -- 12 bottles of ginger beer per year, or about 0.35 l/month. As for liquid in food, I really don’t eat much soup, though I make a good coconut curry at home and I hear coconut milk may have some water in it. My peanut curry also has some water to stretch out the peanut butter to the right consistency. My chili has some water-containing tomato in it, and my salads have water in various veggies & fruits. But of course that’s eating liquid, not drinking it.

    So for 10 months a year, I get 1/20th to 1/25th of the liquid I supposedly need, since tea doesn’t count.

    I guess I’m currently dead.

  9. brucegee1962 says

    Today I saw my first boxed water.
    Still unnecessary, but at least it isn’t plastic.
    Then again, nothing I’ve seen so far about the “plastic in the ocean” problem has convinced me that any but the most negligible part of the great garbage patch comes from the US. I spoke to a geologist recently who said most of it comes from countries where landfills are made too close to the ocean, and then get flooded out to sea during hurricanes. There are many things we do poorly here, and we can certainly take our share of the blame for causing the warming that causes the flooding, but at least we tend to be careful with landfills.

  10. Matt G says

    I live in NYC, home to the best tap water I have ever tasted. You will not be surprised at the astronomical level of consumption of bottled water by residents here. As Bob Dylan sang: “There’s a brand new gimmick every day, just to take somebody’s money away”.

  11. says

    I stopped drinking mains water 30 something years ago, didn’t like the metallic/chlorine taste. We have good rainwater though and I bottle that and take it with me. I don’t mind buying commercial bottled water on occasion as it is clean and convenient when I forget to come armed with my personal supply. And none of our family has any significant dental issues so the fluoridated stuff may not be as important as decent diet and hygiene.

  12. Heidi Nemeth says

    Well hydrated people have full lips. Creases appear on lips, then pits too, as dehydration increases. Cracks, bleeding and flaccid lips mean there’s serious dehydration of longer duration.

  13. John Morales says

    Dunno about you women, but we blokes generally easily get to see whether our urine is particularly concentrated.

    Too strong, better hydrate, no?

  14. Frederic Bourgault-Christie says

    @Holms: The original research was fairly clear, yeah. I remember watching either an episode of Good Eats or Food Detectives, I can’t track it down now, that busted the myth by measuring the amount of water in three meals. Interestingly, unhealthier, fattier meals provided somewhat less water (IIRC), meaning that one may need to drink more water in those cases, but yeah, I remember they found it was about a third of that daily requirement.

    @anat: Bingo. I’ve tried to use water filters and things besides water bottles whenever possible, but when I was in Davis, the water just tasted so bad. Not all municipal and well water has this problem, but a lot do. Friends of mine studied in Arizona and basically lived off of orange soda, bad as that is, because the water was undrinkable and the bottled water was thereby very expensive thanks to supply and demand. I definitely think that approaches like those new flavored air bottles need to be promoted as an alternative, but we also need to find a way of getting municipal water to be more consistent in taste.

  15. khms says

    Tap water -- or any mostly-pure water -- just seems almost undrinkable to me. I like carbonated water (and when it goes flat, bah!), even better with some added taste. Being a diabetic, drinking (as long as it is mostly sugar-free) helps with blood sugar once that gets over approximately 160, at which point it gets washed out with the urine (which is where diabetes got its name). So I’m motivated to drink significantly more than what thirst alone would motivate, possibly 2l or more per day -- I think I’m currently approximately at 18l/week. And I can certainly see the effect on my blood sugar

  16. says

    I buy two to four gallons of water a week for my aquarium. I’d have to treat the local tap water. I use the old water from the aquarium for my insectivorous plants, which don’t like the tap water

  17. springa73 says

    I’m a heavy guy who sweats easily, so in the summer I probably drink close to 8 glasses a day of some fluid or other (water, milk, occasionally soda, don’t drink coffee or tea). In the cooler seasons, nowhere close to that much. I think how much liquid you need varies so much from person to person depending on size, activity level, physical fitness, temperature, humidity, how much liquid in food, etc., that there isn’t any set rule that can be applied generally.

  18. mnb0 says

    @16 JM: exactly. I don’t drink water very often (and hardly ever when bottled, because in The Netherlands it’s quality is worse than from the tap, if anything), because I prefer some taste: milk, tea, juice. In the summer I drink more, it’s as simple as that.

  19. Teve says

    IIRC the 8 glasses of water thing was meant to include the water you ate in food. Most of your food is mostly water.

  20. says

    I do not think it is so much a myth as a too specific generalization. There are people who get thirsty only when it is already late to drink -- like my father, who got himself kidney stones when younger and has to be reminded to drink regularly. I am used to drinking a lot (at least about 2,5-3 l a day, including tea and soup) and when I do not have the opportunity to drink as much as I am used to -- like when traveling for example -- I get headaches.

    As in everything, there is a huge variation between individual people -- some need to drink more, some less, some must have a regime lest they forget, some not. When it comes to health and nutrition there simply is no “one size fits all” rule. Especially not a rule as specific as this one. I mean, a 50 kg bureaucrat in a climatized room surely need not drink as much as 100 kg smelter working near the furnace.

  21. rockwhisperer says

    @5 Ridana, it would be extremely expensive for a water municipality to produce good-tasting water if the source water isn’t there already. I don’t know where the municipalities in the Sacramento area get their water, but I suspect it comes from wells. As the Central Valley has had groundwater overpumped for years. aquifer layers under the ground go dry and wells have to be drilled deeper to reach new layers. The minerals in that layer are not necessarily the same as those in the higher layer formerly being pumped, and so the taste of the water changes. In the Central Valley, that change is usually not for the better, but that’s mostly just a side-effect of the geologic evolution of the valley.

    For places like Sacramento, the usual solution to make city water taste good is to run it through a reverse osmosis system. We have one under our kitchen sink, since the water in the cities of the South San Francisco Bay Area isn’t very tasty. But there’s an initial investment, filters need changing every few months (more often if your family is large), and RO uses far more water than actually ends up available at the special drinking tap. Poor people just get to drink crappy water or buy bottled. It would be horribly expensive and water-wasteful to simply process an entire city’s water before it is piped out to consumers.

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