Are 8 Glasses of Water Necessary?

Can other drinks such as diet sodas and herbal tea count towards my 8 glasses of water for the day? "The fluids consumed do not have to be only water. Individuals can obtain their fluids from a variety of beverages and foods. Contrary to popular opinion, consumers do not need to consume 'eight glasses of water a day' to meet their fluid needs."
Source: Institute of Medicine of the National Academy of Science Read more ...