I don’t know about the OP one way or another, but I was always annoyed the way people always say “8 glasses of water” without specifying how big the glass is.
I mean, glasses are all different sizes. A glass can range from a little 4 ounce glass for grapefruit juice to a huge 20 ounce glass for iced tea. If you mean 8 ounces, would it hurt you so much to actually say 8 ounces? How do you expect me to know how much a “glass” is? Actually, there is a fluid measure of 8 ounces, but its name is “cup.”