i'm guessing you're about to replace it and thats why you're asking the question...
I actually replaced mine about a month ago. Went to the local autoparts store ( Autozone, if there's one around there ) and picked up a replacement. They have two there, one is the stock replacement and one is a "high performance" (words of the salesman ) water pump. I just got the stock replacement and paid only about $20 for it. Works fine and its under warranty from autozone .