No. Water will only make you lose fat in combination with exercise and healthy food.
If you only drink water for a certain time, just to lose weight, it won't help you at all.
Water is vital anyway. It's good for your skin, prevents you from having cringes/bags under your eyes and does amazing things to the inside of your body overall.
Also, try to drink at least one liter to two liter water per day. It's much better than sugary drinks.
If you're trying to lose belly fat, you should also lose the sugary drinks. They are one of the reasons you have belly fat anyway.