How much water should you drink a day? Does it even matter?
Briefly, the answers are: yes, it matters, and you should drink when you're thirsty. The result will be that you'll probably drink about 3 quarts of water per day, and that will be perfect.
You can monitor how much water you're getting by the color of your urine, which should be pale or almost clear.
You can also get too much water, which is possible if you're forcing yourself to drink more water than you want.
And it doesn't have to be plain water that you drink!
Since we're made of about 60% water, we obviously need it, and it must be included as part of our nutrition.
How important is water?
Well, it's interesting to note that the average human can easily survive six weeks without any food. (Yes, really. Have you ever heard of 40-day fasts? I know of several people who have done it.)
However, go one week without water, and if you don't die, you will be in the hospital.
Your body can store lots of food in the form of fat. The more fat you have, the longer you can live without food.
It's not the same with water. Your body stores lots of water, but since it's part of every body process, a major constituent of blood, evaporated to cool the body, and needed by the kidneys and intestines to purge waste, it's used up quickly. You'll be in danger of medical problems after just 3 days without water.
If you drink too little water, you will get thirsty, and perhaps even sick. If you drink too much water, you could die.
Runner's World reported once that there are deaths at marathons every year from hyponatremia. Hyponatremia is low sodium. Sodium, and other electrolytes, allow the fluids in your body to conduct electricity better. Without enough, systems in your body go haywire, and you can die.
Athletes who work hard in the heat, such as marathoners, are constantly warned to drink lots of water, but this can be highly dangerous. Dehydration will make you sick and hurt performance. Over-hydrating without replenishing electrolytes, especially sodium (from salt), can and does kill. (See Mayo Clinic article and this one from sportsmedicine.about.com.)
If you are going to work or exercise in the sun, drink a sports drink, not water.
Of course, this is unlikely to be dangerous if you're simply working in the yard one day, both because it's not as strenuous as a marathon and because yard work is still done more by men. Men are larger and so it takes a larger amount of water to dilute their fluids.
Marathoners and other extreme endurance sports athletes, who are prone to being smaller anyway, need to take this warning very seriously.
You get water both by drinking and from the food you eat. For humans, however, the majority comes by drinking.
The rule generally given is "8x8." That refers to drinking eight 8-oz. cups of water each day.
The rule is dumb. You should drink when you're thirsty instead.
Here's the rules for how much water you should drink per day that aren't fairy tales ...
These rules for how much water to drink are based on numerous articles I've read on the internet and in health and science magazines. I've been careful to only accumulate advice from articles that quote reliable studies.
However, how can you know how good I've been at that? So here's a couple of quotes from the Mayo Clinic concerning a couple of my rules, so you can have some confidence in this advice:
Eight 8-ounce glasses of water a day: ... Although the approach really isn't supported by scientific evidence, many people use this easy-to-remember rule ... (emphasis mine)
The Institute of Medicine advises that men consume roughly 3 liters [very close to 3 quarts, what I recommended] of total beverages [not just water] a day and women consume 2.2 liters [about nine 8-oz. cups]. (emphasis and brackets mine)
If you drink enough fluids so that you rarely feel thirsty and produce 1.5 liters (about 6.3 cups) or more of colorless or slightly yellow urine a day, your fluid intake is probably adequate. (parentheses theirs)
Exact same advice I just gave you. We're being careful here!
As I said, I'm very careful to give you supported, reliable advice. Check out anything I write here, and you will find sites like the Mayo Clinic and the National Institutes of Health agreeing with me because I only lean on articles that back up their advice with solid research.
Caffeinated drinks do not dehydrate you, especially if you're an athlete. Yes, they make you urinate more, but so does water. Both, however, hydrate you; neither dehydrates you.
Says who? How about the Mayo Clinic? ABC News' Dr. Marie Savard agrees.