Everyone beat me to suggestions. =D
If you want to continue giving him water in a bowl(instead of using a bottle), I suggest either what Blue_Frog gave a link to (we have one to put Larry's food in)... but they usually aren't that big, so it would probably need to be refilled quite often..
Or, what I would go with, a Ceramic food bowl. I use them for my rats' food, and they haven't managed to tip it yet. Of course, rabbits are bigger than rats. =)

There is the kind that you can find in almost any petstore, and come in alot of different sizes and such. They're pretty heavy.. so they're not easily tipped over.