How much water should a normal?

Nice information, many thanks to the author. An average adult should consume 2.5 litres of water daily & this intake needs to be increased during summer or during physical activity.

Every system in your body depends on water. Water is your body's principal chemical component and makes up about 60 percent of your body weight. A normal person should drinks 10 to 12 glasses of water daily

I find the differences in opinion here interesting. The general consensus seems to vary from 2.5 liters to 4 liters of water per day. Like I said earlier, I usually drink three, but I've been thinking about increasing it to 3.5 or 4. Maybe it's because of the warm weather, but I've been feeling like 3 just isn't enough lately.

10-12 glasses is right but intake should go up in summer, exposure to heat, strenuous sports/ games that result in lot of sweating. Since the query is normal healthy adult I am not mentioning situations like vomiting, loose stools, infections etc.