Some people need more water than others. I used to drink a gallon every day when I worked in the heat...but then I also sweated a lot. Now I'm limited to two liters per day, plus what I sweat...which is hard for me as I'm a water drinker normally.
You could try monitoring the color of your urine. The lighter, the better. You don't want to get dehydrated, so dark is bad.
Someone suggested adding things to your water for flavor, like lemon, orange, cucumber, mint leaves, ginger...get creative. I do the lemon, have done the cucumber (let it set overnight in the fridge for best results) and even tried the orange once. I used to put mint in my iced tea, but it quit growing in my back yard.
Hope you figure out what works for you.