The average is one bottle per hour, but that means average rider, average weather, average terrain, etc. When I use to live in the Mojave Desert area of California in the summer I consumed 1 24 ounce bottle per 30 minutes, but now that I live in NE Indiana on a cool day I may consume 1 24 ounce bottle in 1 1/2 hours. On the average you take 2 gulps every 15 minutes.
Weighing yourself before and after a ride is one way to tell if you got enough water, if you weigh less afterwards you didn't drink enough. Another way is the color of your urine, note I said color not taste, anywho, if the urine is yellow to dark yellow you didn't drink enough, it should be a pale yellow. And yet another test is to pinch some skin at the wrist about 1/4th of an inch and let go it should go back to it's original position in less than 2 to 3 seconds, a slow rebound means not enough liquid in your system.
You don't want to drink too much either or else you could suffer from hyponatremia which can kill you.
To prepare yourself for a ride you should drink about 16 to 34 ounces of water over a period of about an hour about 4 hours before the ride, then about 2 hours before the ride you drink another 12 ounces taking about an hour to drink it. When you return drink another 24 ounces over a period of an hour, that drink should be a electrolyte replacement drink.