Why does my cat vomit after drinking water?

United States
@dvmurphy (326)
December 19, 2009 1:04pm CST
My cat demands fresh water from a running tub faucet several times a day but after he drinks he will go eat his dry cat food and then vomit water several times. It is always just water and cat food with no hair so I doubt it is a hairball. He is allergic to wheat so he is on a special blend of cat food. This has been going on for a while and the vet says it is because he is drinking alot and then wolfing down his food. Is this normal? He is nearly 10 yrs old and is th only cat or animal in my house.