how much is a glass of water?

S • 29. Mama to a rainbow boy. Pregnant with #2.
Ok stupid question, but how many ounces do you count as 1 glass of water? 
I typically drink 6-7 16oz bottle waters. 
Now my dr wants me drinking 10-12 glasses of water and I don't think I can't literally drink that much is it equates to 10-12 bottles.