Australia New Guinea Pig owner

Hi everone, i have only just gotten my first ever guinea pig about 3 to 4 weeks ago. His name is Frodo and his soo cute. But i have just noticed that sometime his pee is white and drys like white paint, it doesn't stink and it doesn't seem to bother him. I think it could be because of lack of water. Everytime he drinks he doesn't seem to have the problem. any ideas?