PB says to drink when you are thirsty. Personally, I try to get 1/2 my body weight in ounces daily (85 oz for me, but if you were to weigh 200 lbs, you'd drink 100 oz). I have a 30 oz mug that I fill up a couple times a day. It gets the job done pretty easily.
You could also look into sparkling mineral water or buy your own water carbonater & add some fruit juices to it.