[JoeyP]

This is a problem with Yorkies
They do get riled up and its one reason why they aren't too good with children
I see this with my Zach
when he gets excited its like he goes in to a hyper state
I don't think he would ever bite but this is the type of emotional state where biting can occur

You're going to have to work with your dog
if water gets him excited you can desensitize him slowly by exposing him to it while trying to keep him calm at the sametime
kids running and jumping are always going to make a dog hyper
so you're going to have to keep watch when ever thye are around