Perfectly normal when you're starting out. The increase in water intake should happen gradually.
Two things to keep in mind:
1 - 8-10 glasses of water per day includes water that is present in other foods/drinks.. (i.E. Juices, pasta, etc.).
2 - 8.10 glasses of water is for the average person. If you're larger or smaller you should adjust your water intake accordingly.
Personally, I drink no less than 1 gallon. (around 4l) of water per day. But i'm also larger than your average guy.
So as I said, increase your liquid intake gradually and allow your body to begin absorbing this water. Also note that dieuretics will make you urinate more frequently. (i.E. Caffeine products such as coffee, or alcohol.)