Dehydrated

Is it possible to be dehydrated when you drink like 90 ounces of water a day?! Seriously. The last few days I've been really light-headed, which is typically a sign that I need more water. But literally, I've been drinking inordinate amounts of water because I have a water bottle that is over 32 ounces and I usually fill it up about 3x during the day. I can't possibly be dehydrated. And I haven't been doing any particularly strenuous exercise that would require me to replenish at a higher rate. This is very bothersome.