Im 210 pounds 5'6 eating 500 calories a day and drinking water how much weight will i loose in a week?

Too many variables to answer completely, even though you tried!

Gender, age and activity level is important as well.

If you are relatively active and in your late teens, this will probably result in losing about a pound a day. But if there isn't enough to keep you active and you get lazy, it would be a lot less, and your body could go into a starvation mode, and be very sluggish and actually gain weight.