There have been some discussions recently on the TPCUG health newsgroup about how much liquid the body needs. The general belief is that we should drink at least 8 glasses of water a day with some recommendations on having lots of water by your side and sipping as often as you can.
This article, however, shows a different view:
Still, I am sticking to having hot water on my desk. It does feel strange at first, but you get used to it quite fast. Supposedly has lots of benefits, but could be just a myth like the above.