1999 Dodge Caravan water pump and timing belt replacement

Engine stalled and my mechanic says that timing belt broke and needs replacement. My mechanic also wants to change water pump, but I think the water pump does not need to be replaced since it was OK and not leaking, also I do not see any relationship between timing belt and water pump. I am wrong?
My mechanic says that normally water pump needs replacement once it is removed, and in this case it was necessary to be removed. This is puzzling me also.