Water Retention

I'm a 140 lb female who drinks over a gallon of water a day. According to the recommendation that you should drink half your body weight in oz this about double the recommended amount.

Question is I work at a desk all day, and by the end of the day I feel like my legs, especially my calves, are tight, heavy, and maybe even bloated. If I go to the gym or for a run after work it helps to get rid of the feeling but it usually doesn't go completley away till morning.

I'm thinking maybe I'm drinking too much water but I was always under the impression that you really couldn't drink too much water.