Congrats bro! But you shouldn't just drink water lol. I hope you're not starving yourself, cause what you REALLY want to do is to increase your metabolism by working out more and eating regularly. Do full body workouts like running, swimming, playing a sport. And do compound lifts like squats, deadlifts, pull ups, and bench pressing. But it all comes down to dicipline and consistancy. If you set your mind to a goal you'll reach your goal weight in no time!