Water weight loss , Maximum?

Ferniand

So here's another question(s) since you guys are so helpful and I like to know more

What's the maximum amount of water weight loss in a week? I've lost 5 Pounds in my first week , Is this mostly water weight? Will i keep losing this much weight weekly? I'm guessing it's not safe , but i'm also assuming a lot of it is water weight which I will gain back.

Also , I've noticed quite the difference on my stomach as it looks slimmer and healthier somehow. Is this possible from 5 pounds loss? Or is it just me overrating my weight loss :P