Almost everyone in the fitness, conditioning, and nutrition field mentions a minimum of 8 glasses of water per day. Most recommend a GALLON a day. Physicians see this as a fad. It may be largely promoted by companies that sell bottled water and water filters. Consumer Labs have tested over and over again that bottled water is NOT better than tap water. I remember when water was free and no one walked around with a constant liter or gallon sized bottle with them.
I can’t imagine how 1950’s laborers and athletes survived without a gallon jug around them for twenty four hours a day.
Try doing a search at Plug “water” into the search function to read about the evolutionary reasons for water drinking.

Here is some data from the Urban Myth site, Snopes.–

Maybe they should put free internet in the public bathrooms. Most of you have lots of wasted time there anyway.