Do you really need 8 glasses of water per day?

I drink the blood of my fallen foes from the arena.

Divide your body weight in half and that's how many ounces of water you should be consuming daily. (Example: 140lbs / 2= 70lbs = 70 ounces = 8.5cups) Other things like weather and physical activity play a part in how much you should be drinking. Keep in mind this doesn't have to be pure water your daily water intake is also reached through food and other juices. (Not 100% sure about the last bit)
Just drink till your piss is clear

Well, you don't *need* them, but water is very good for you. I know I think a lot more clearly, concentrate better for longer and feel a lot more energetic when I'm drinking more water. When I need to be super productive for a few weeks, I reckon I drink at least 3 litres a day, sometimes 4. So long as you're sensible and don't drink it all at once, it's difficult to drink too much water.

How you drink it is as important as how much. I drink water slowly and incrementally, even when I'm not thirsty, to keep my mental and physical energy high.

Ha! No.
I probably only drink maybe 1-2 glasses of actual water. I drink other stuff... I dislike the taste of water so I usually drink fruity sparkling water anyway. I don't exercise or sweat much so I really don't think its that big of a deal.
I think telling everyone a certain amount of water is 'perfect" is dumb, just go with what your body is telling you.

Yes.

Water......OOHHHHHH! you mean Kool Aid.

Like what the others have said, you need to consider your body weight, daily exercise, local weather etc. You also need to consider what kind of food you're eating. If you eat foods that are high in salt, it'll leave you feeling thirsty and your body will naturally want to drink more water. Otherwise, if you eat food with high water content, you won't feel the need to drink as much.

Well, it depends on you. I usually don't drink water ^^;