I have the finger brush, but he bites me!
So I got him a toothbrush and he watches me brush mine and copies me, but when he reaches down for the water he just sucks the brush to get the water...he's not actually "brushing"
any suggestions. (i try to do it for him but he pushes me away)

Re: tips on brushing LO's teeth
We actually use 2 toothbrushes. I give DD one so she can try to brush her teeth and I use the 2nd one to actually brush her teeth. Sometimes she tries to suck or bite the brush. I just tell her to "open up" and then I start brushing again.
To make it more fun, you could get a firefly toothbrush. They have them at Walmart for about $1 each. They light up and flash when you press the bottom of the brush. It's good for keeping LO's entertained. And I think it's supposed to flash for as long as you're supposed to brush. My DD knows that when it's done flashing that teeth brushing time is over.
We do this too. But my BFF is a pediatric dentist and she said to google lap tooth brushing. Put his head in your lap upside down. DD hates it but is supposed to be the most effective way.