I like to drink a lot of water, I admit that. But the last time I went to my favorite asian buffet restaurant the server walked over to me with a glass of water, and a full pitcher and just left both at the table… without asking me if I wanted it or not. I know I usually ask for 2 refills in my water, but that is normally because it is full to the top with ice, and I get one decent pull off the glass and its empty, not that I actually drank a full glass, it is more like 2 ounces of liquid! I was not happy, and actually felt embarrassed and slighted. I tip over 20% and feel I deserve to have my water glass refilled just like everyone else. If they don't want to come back every few minutes to do so then kindly put more water than ice into the glass and leave me to decide what is enough water to drink.
I left a .38¢ tip that day, because the only time I saw that server was once for the water, and when she removed my plate and dropped off my check. I normally tip $2.38 on a $7.62 check. (I normally just leave a $10 bill)