I honestly never keep track of how much water I drink. It's my ADB (All Day Beverage) so I always have a bottle or glass of water with me. Been like that for several years, even before I started vaping.
I wouldn't sweat quantities; they vary for everyone based on temperature, humidity, and activity level (sorry, the "eight glasses a day" does NOT apply equally to all people) but if you're feeling dry, you probably are.