• Six glasses is usually enough. If you must count, 6 glasses of water a day is probably a good rule of thumb (not a bare minimum). But the average person, doing gentle activity in a gentle climate, can probably get all the fluid they need from solid food alone (although it’s not recommended).
• Follow your thirst. Your need for water varies greatly depending on your activity level. Fortunately, your body is surprisingly good at telling you when to drink. And the idea that we’re chronically (and unknowingly) dehydrated is little more than science fiction.
• Don’t fear coffee and tea. Despite the diuretic properties of caffeine, you’ll still retain a large amount of the fluid in every cup—and even more if you’re a regular drinker of caffeinated beverages.
• Dehydration may worsen constipation. If you’re straining to pass stool, you might benefit from increasing your water intake a bit. However, results vary, and a more likely cause of constipation is inadequate fiber in your diet.
So why are we so easily misled by drinking myths that don’t hold water? Quite simply, in the era of modern science, we’re used to hearing (and accepting) startling facts. But when it comes to water, medical research is in an unusual position: proving that our common sense was right all along.
Source of Information : Oreilly - Your Body Missing Manual