If you are a woman who has ever tried to lose weight you may have heard or read the urban myth about eight glasses of water a day. I have heard it both as diet advice, that it would "melt" fat, and also as health advice. As far as the "melting fat" it didn't work for me. Eight cups of water made me have to go on bathroom breaks a lot more. It didn't have the desired effect of washing the pounds off of me. As far as the health benefit, even that has come up to be suspect. It's a bit of an urban myth. Human beings do need water to survive. No doubt you die quicker for lack of water than for lack of food. As far as the eight cups goes, there are a couple of parameters not always mentioned.
First of all, there is a difference between eight cups and eight glasses. A lot of tall glasses hold sixteen or more ounces. The average soda bottle represents more than 2 servings, almost 2 and a half. So the amount of water it would take to make eight cups is probably less than you think. The second thing I learned was, the eight cups is all water total in a day, including the liquid found in food, such as citrus friends and juices. So if all you want is the survival benefit of drinking water, you don't have to go overboard scheduling your drinks. Just drink whenever you are thirsty and you will probably get enough.
As far as the health benefit: it is important to drink clean water. To that end, most tap water in major cities is clean enough. The water you keep around in bottles is more stagnant than tap water. The plastic bottles create landfill. And especially once the bottle has been opened there is a greater risk of bacteria in the bottle than in regular running tap water. If you are worried about tap water you can have it tested, or get in the habit of letting it run a moment, to clear out the pipe before you drink it. IF you are still uncomfortable, buying a brita pitcher, a Berkey filter, or a reverse osmosis system are all possibilities.
If you have moderate funds and moderate needs, a filter pitcher such as made by Pur or Brita are the most reasonable options. The filters have to be replaced about once every two months. IF you are a long term renter you may want to buy the filter that screws right onto your faucet. It still has to be periodically replaced, but it's a little more immediate than waiting for the pitcher to filter. IF you are a long term renter or home owner with more money to invest the Berkey systems are certainly impressive in their ability to filter just about anything. Use a search engine to find a reputable dealer. These systems do not have to be attached to your current plumbing system, so you can move them when you move. If you own the house, a reverse osmosis system is the most convenient. The filters still have to be changed, however, all sink water comes out of the tap clean and ready to drink.
Once you have clean water available to drink the next question is, how come drinking the eight cups didn't melt my fat? IS it all bunk? I'm going to go with a qualified "no." Whereas there is no reason to think water has magically fat burning abilities, it CAN be used as a diet aid. The thing to do is REPLACE all other liquids you drink with water. If you were willing to give up soda, even diet soda, milk, juice, and any other calorie filled liquid with water, you would lose weight. Also there's really no nutritional reason a healthy adult needs to drink sodas and juices. The vitamin C in juice is better absorbed if you eat it in fruit, plus eating it in lieu of drinking it means less sugar in your diet.
Soda has no nutritional value. There's actually no reason in the world to ever drink it, except that humans are addicted to the sweet sugary taste. But why do we have to give up diet soda as well? The fake sugars are more dangerous to health than real ones are. Many a cause cancer in rats, and migraines in humans. In addition, studies show that drinkers of diet sodas consume more over all calories than drinkers of regular sodas because of the psychological effect. Consumers believe because they "saved" calories on their diet drink, those calories can be spent on fatty cakes, cookies and goodies. The net effect is detrimental. So stay away from diet soda. Black and green tea are actually good for people and have anit-oxidant effects, but once again, only if you keep the sugar and the milk out of the drink. The two teaspoons of sugar in cup of tea is less than the 16 grams from a soda, but you don't really need it. Putting milk in tea negates the anti-oxidants, so don't do it.