Weight loss...

Hey ladies I have a question I'm 5'3 and I did weigh 205 the last time I weighed myself 3 weeks ago and I was just recently told I look like I lost a lot of weight I weighed myself and I currently weigh 195 and I haven't been doing anything different except drinking a lot of water and I'm not usually a water drinker.. is it normal to lose 10 pds in 3 weeks? Is it because of the water? Should I be worried?