On the "too much water" issue — sure, it’s possible, and it can lead to hyponatremia . Bad.

More generally, the Institute of Medicine’s recent guidelines on water intake are interesting. An excerpt from the linked article about the guidelines:

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True or false?

  1. Health and nutrition experts recommend drinking eight or more 8-ounce servings of water daily.
  2. You should not wait until you’re thirsty to drink water. By the time you feel thirsty, you have lost a significant amount of your total body water composition.
  3. Caffeinated beverages such as coffee, tea, and cola, along with alcoholic beverages, can cause dehydration by lowering the net total of hydrating beverages such as water.
  4. Because the thirst mechanism becomes blunted with age, older people, in particular, need to make a conscious effort to drink eight glasses of water daily.
  5. For men, an average of 16 cups of water a day is adequate; for women, an average of 11 cups.
The only statement that’s true is the last one.

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The basic message of the guidelines is that most Americans consume plenty of water simply by drinking when they are thirsty and eating a normal diet. My own opinion is that excessive water intake will not help PE in any way.