First of all, I just wanted to 'remind' you to make sure you change his water throughout the day since all cats like fresh water
Have you been watching his water dish to see if the level of water has went down at all? He's still a kitten so you may have to show him a few times where the water is, and that its ok to drink from that bowl! Most importantly, don't get too worried about it... he'll get used to it and start drinking water like crazy! But if your still concerned after a few days that he isn't drinking- call up your vet- he could be getting dehydrated!
It depends on what your cat is eating - if it's wet food you won't see him drinking much and that's fine as he'll be getting most of his water with his food. If dry then he needs to be drinking a bit more, but kittens do usually drink enough. When I first got Mosi he always had a drink of water straight after eating dry food. Now that he has wet food I don't see him drinking much but he does drink sometimes. Some cats prefer fresh water but others seem to prefer it after it's been standing a while so it might be a good idea to have more than one water bowl and make sure one contains fresh water and the other water that's been down a while in case he prefers that.