Anthony Robbin's bulletin board has an interesting post about water...

Click on the title of this post to read it all, but I was surprised by this body builder's statement that... A non active person needs a half ounce of water per pound of body weight per day. That is ten 8 ounce glasses a day if your weight is 160 pounds. For every 25 pounds you exceed you ideal weight, increase it by one 8 ounce glass. An active, athletic person needs 2/3 ounce per pound which is 13-14 8 ounce glasses a day if you're 160 pounds. The more you exercise the more water you need. Spread out your water intake throughout the day. Do not drink more than 4 glasses within any given hour. After a few weeks your bladder calms down and you will urinate less frequently, but in larger amounts. . Sue :)