While it may be a valid recommendation, drinking that much water every day is not as important as consuming enough liquid. My point being that the liquid that you ingest does not have to come via an actual glass of water - milk, juice, and other liquids present in foods do count toward your total. Additionally, the signals produced by the body indicating dehydration are often confused for hunger pangs so proper hydration can prevent overeating and can be a factor in weight loss.
It is important to remember that not all liquids are created equal when it comes to hydration. One reason why water is recommended is because it doesn't carry any unwanted calories. Beverages that include caffeine or other diuretics can cause the body to eliminate more liquid than they provide so coffee, cola, and tea may not always be the best choice to quench your thirst.
Personally, I almost always have a glass of water within reach. We installed a faucet-mounted water filtered several years ago and it has turned out to be a major savings over bottled water. You can check out my analysis of it in an article I wrote 3 years ago - The PUR Vertical Faucet Filter with Three-Stage Filtration.